This paper attempts to examine the long-term changes of cross-sectional variations in Japanese time use behaviour by establishing a multilevel multiple discrete-continuous extreme value model. The model describes both activity participation and time allocation behaviour by incorporating two different unobserved variation components: interindividual variation and spatial variation (at the prefecture level). The incorporations of such unobserved components into the discussion of long-term changes can provide information on changes in the diversification of activity-travel patterns. An empirical analysis was conducted by using national time use data at four points in time (1986, 1991, 1996, and 2001) from the "Survey on Time Use and Leisure Activities" collected by the Ministry of Internal Affairs and Communications in Japan. The most important finding from the empirical analysis is that given the explanatory variables used in this study, Japanese time use behaviour has certainly changed toward increasing effects of unobserved interindividual variations. This implies that a stochastic nature in behaviour becomes more dominant as time passes, suggesting some new challenges for describing activity-travel patterns in the long term.