21 Million Non-Regular Workers — Has 'Equal Pay for Equal Work' Narrowed Japan's Employment Gap?
36.8% of Japan's employees—21.26 million—are non-regular workers. Monthly wage gap: ¥116,000. Five years after equal pay legislation, gaps persist.
What Is Happening
21.26 million. 36.8% of Japan's employees (excluding executives) work in non-regular employment (Ministry of Internal Affairs and Communications, Labour Force Survey, 2024 average). Against 36.39 million regular employees, the combined total of part-timers, arubaito (casual part-time), dispatched workers, contract employees, and shokutaku (post-retirement re-hires) exceeds 21 million. This ratio has risen almost continuously over the past two decades.
The crux of the problem is that differences in employment type translate directly into disparities in wages, social insurance, and career development. According to the 2024 Wage Census, the monthly scheduled earnings for regular employees stand at ¥349,000, compared to ¥233,000 for non-regular workers. The gap index is 66.9 — non-regular wages remain roughly two-thirds of regular pay.
| Category | Monthly pay | Gap index |
|---|---|---|
| Regular employees | ¥349,000 | 100.0 |
| Non-regular employees | ¥233,000 | 66.9 |
Gender gap index (regular = 100)
A monthly gap of ¥116,000. On an annual basis, including bonus differentials, the gap exceeds ¥2 million. Larger firms show wider gaps (index: 61.2).
Source: MHLW Wage Census 2024
On an annual basis, this gap widens further. Bonuses are the decisive fork. Regular employees receive over ¥950,000 in annual bonuses, while non-regular workers receive substantially less or none at all. The annual income gap comfortably exceeds ¥2 million.
Moreover, the gap expands with age. At age 19 and under, the monthly differential is approximately ¥22,000, growing to ¥53,000 in the 25–29 bracket and widening further through the 50s. The seniority-based wage structure that applies exclusively to regular employees amplifies the disparity over time.
Background and Context
Inside the 21 Million — Who Works Non-Regular, and Why
Breaking down the 21.26 million non-regular workers, the largest category is part-time (approximately 10.35 million, 48.7%), followed by arubaito/casual part-time (4.59 million), contract employees (2.84 million), dispatched workers (1.46 million), and shokutaku/post-retirement re-hires (1.12 million).
Gender composition
About 70% of 21.26 million non-regular workers are women. Part-time is the largest category, predominantly married women. Workers aged 65+ in non-regular roles reached 4.33 million (+160,000 YoY).
Source: MIC Labour Force Survey (Detailed Tabulation) 2024
A pronounced gender skew exists: 67.9% (14.44 million) of non-regular workers are women. The spousal deduction and Category 3 insurance systems have historically incentivized part-time work, shaping this structure. Among men, 6.82 million are non-regular. Particularly notable is the rising non-regular ratio among young men: 51.0% for ages 15-24 (up from 21.4% in 1991) and 14.8% for ages 25-34 (up from 2.8%). The structural shift since the 1990s has been dramatic.
The most cited reason for choosing non-regular work is "wanting to work at convenient times" (7.31 million, 2024 average). While voluntary choice constitutes the majority, "involuntary non-regular" workers — those who could not find regular positions — still number 1.70 million (8.7%). Although this rate has fallen to a record low, 1.70 million in absolute terms is far from negligible.
Equal Pay for Equal Work — Assessing Five Years of Implementation
The "Equal Pay for Equal Work" mandate (Part-Time and Fixed-Term Employment Act) took full effect for large enterprises in April 2020 and for SMEs in April 2021. After five years, both achievements and limitations have come into focus.
Where progress has been made: allowance corrections. For items with clear justification — commuting allowances, meal subsidies, year-end holiday pay — the Supreme Court's October 2020 rulings (Japan Post cases) found non-payment to non-regular workers "unreasonable." Corporate compliance accelerated in response.
Where stagnation persists: base pay and bonuses. The same court (Osaka Medical and Pharmaceutical University and Metro Commerce cases) found that non-payment of bonuses and retirement allowances was "not necessarily unreasonable." This judicial signal arguably gave employers cover to maintain the status quo on core compensation.
A potential turning point arrived in November 2025 when MHLW published a revised guideline draft. It stated that bonuses "must be paid to non-regular workers when the purpose is applicable" and that withholding retirement benefits without alternative measures "could be deemed an unreasonable treatment disparity." The policy focus is shifting from allowance correction to base pay and bonus equity.
International Context — The Peculiarity of Japan's "Non-Regular" Category
In OECD statistics, Japan's "temporary employment" rate is 11-13%, close to the OECD average. However, Japan's "non-regular employment" at 36.8% includes a large volume of indefinite-contract part-timers, making direct international comparison problematic. The OECD has repeatedly noted that "disadvantages in wages and social protection for non-regular workers are significant" in Japan — the depth of treatment gaps by employment type stands out even among advanced economies.
Reading the Structure
The problem of non-regular employment cannot be reduced to individual choice or effort. A structural inequality mechanism exists here, one in which employment type cascades beyond wages into social insurance, housing, and family formation.
Non-regular employment extends beyond individual economic instability, cascading into family formation, housing security, and social insurance coverage. The notably lower marriage rate among non-regular male workers is repeatedly cited in government reports as a structural driver of declining birth rates.
Source: MHLW National Life Survey; Children & Families Agency (2025)
The relationship between male non-regular employment and marriage rates illustrates this structure most starkly. Among men in their 30s, the tendency for lower incomes to correlate with higher unmarriage rates has been consistent since 2012; non-regular men frequently cannot afford to marry. The Children and Families Agency explicitly identifies the expansion of non-regular employment as one structural driver of declining birth rates. Marriages fell to 475,000 in 2023 — the causal chain from non-regular employment to low wages to marriage difficulty to birth rate decline is now visible at the demographic level.
The decline of involuntary non-regular employment to 1.70 million does, in one sense, indicate labor market improvement. Yet as long as those who "voluntarily choose" non-regular work continue earning two-thirds of regular wages, "freedom of choice" and "fairness of treatment" remain unreconciled. A state in which the only options available are structurally disadvantageous can hardly be called genuine freedom of choice, even if the selection is voluntary.
The 2025 guideline revision's move into base pay and bonus correction carries significant weight. Whether judicial precedent and administrative guidance alone can reshape wage structures, however, remains an open question. The risk that companies achieve improved gap indices through "downward equalization" — cutting regular employee benefits rather than raising non-regular pay — has already been flagged by some analysts.
The structural analysis of unemployment rates demonstrated the "quantity-quality gap" in employment; non-regular employment provides corroborating evidence from a different angle. The 14-day consecutive work limit and rest interval regulation discussion on working-hour rules is equally relevant to how non-regular workers are treated. In an era where quantitative "labor shortages" are loudly proclaimed, the question of how to design conditions for 21 million non-regular workers is synonymous with interrogating the structure of Japan's labor market itself.
References
Labour Force Survey (Detailed Tabulation), 2024 Annual Average
Statistics Bureau of Japan. Ministry of Internal Affairs and Communications
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Basic Survey on Wage Structure, 2024 Results
Ministry of Health, Labour and Welfare. MHLW
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Equal Pay for Equal Work Guideline Revision (Draft)
Ministry of Health, Labour and Welfare. MHLW
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OECD Employment Outlook 2025: Japan Country Note
OECD. OECD Publishing
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