This paper deals with reduction in the peak-hour travel demand by staggered office hours, and survey data gathered in Hiroshima Urban Area are used. Work travel is analysed in terms of arrival time at work place, departure time from home, and mode choice. The effect on out of home activities of commuter is also studied. It is proposed that the characteristics of work travel is explained by not only official work start time but traffic condition, kind of workshop, and attributes of commuter. Some implications for traffic demand control by staggered office hours are considered.