This paper examines time spent on housework by not working husbands. Analyses in this paper are based on data of 2006 Survey on Time Use and Leisure Activities conducted by Statistics Bureau, Ministry of Public Management, Home Affairs, Posts and Telecommunications, Japan. Housework includes cooking, cleaning, laundry, caring for adults, household chore, child care and shopping. Not working husbands spent more time on housework than employed husbands on weekdays. On Sunday, the amount of time devoted to housework by not working husbands was the same as employed husbands. Not working husbands at the child care period devoted a large amount of time to housework. Not working husbands with employed wives spent more time on housework than those with not working wives. Not working husbands, however, did not replace their wives as the primary person responsible for the housework.