As the population ages, older adults are increasingly expected to play multiple productive roles. This study examined how hours of paid or unpaid work were associated with volunteering among older Japanese. Data came from the 2012 National Survey of the Japanese Elderly, a nationwide survey of Japanese aged 60 and older (N = 1,324). We performed multinominal logistic regression analyses to predict volunteering (regular or occasional versus non-volunteer) based on hours of paid work and unpaid work for family consisting of sick/disabled care, grandchild care and household chores. Those who worked moderate hours were most likely to be a regular volunteer while working 150 hours or more per month had a lower probability of volunteering, regardless of whether the work was paid or unpaid. Thus, full-time level work competed with volunteering for both paid and unpaid work for family, but it was more so for paid work. By types of activities, doing household chores and substantial grandchild care were positively associated with volunteering, and the latter complementary relationship was explained by a larger community network among grandparents. Our findings indicate that delaying retirement from full-time paid work may reduce the supply of regular volunteers in the community. Thus, policies to increase part-time work for older adults as well as the types of volunteer work in which paid workers can participate are necessary.