This study used a diary method and investigated the relationship between self-reports of depressive symptoms, and engagement in “pleasant and unpleasant activities” as well as affective reactions to these activities in Japanese undergraduate students. First, participants (N=121) monitored, for one day, whether they experienced each activity that was included in “the Scale of Life Events in Interpersonal and Achievement Domains for Undergraduate Students” (Takahira, 1998) and rated the degree of affective reactions to each activity. Participants also responded to the Beck Depression Inventory (BDI). Result revealed individual differences in the level of positive and negative affects following experienced activities. Second, based on the BDI scores, we selected depressed (n=34) and nondepressed (n=34) groups of students. Pleasant and unpleasant activities were respectively defined as those activities that individuals rated and followed by positive or negative affect evaluations. Result showed that the depressed group reported significantly less pleasant activities, more unpleasant activities, and a higher level of negative affect following experienced activities. The two groups did not differ significantly in the levels of positive affects. These results demonstrate the importance of conducting an accurate assessment of specific daily activities and associated affects in understanding depression.