This study uses repeated cross-sectional data from 1982 to 2007 to understand labor force behavior of men in Japan, focusing on the increase in non-regular employment. I find that regular employment fell significantly for recent cohorts of less-educated men. Regular employment of single men and less-educated married men responded more to the business cycle than did regular employment of highly educated married men. Cohorts who finished their schooling in the late 1990s and early 2000s experienced a severe decline in regular employment at young ages, although this phenomenon was mainly observed among single men and not among married men.