Cognitive Behavioral Therapy (CBT) shows promise for the effective treatment and prevention for depression. During the long-term treatment with CBT, users (e.g. patients with depression) are given some kind of homework in their daily lives to self-monitor their thoughts and behaviors by using some techniques taught by therapists (e.g. doctors) in the face-to-face session. In this paper, we present an applica- tion to support users to do their homework, especially self- monitoring of their behaviors. By collecting lifelogs of them via smart phones, the application estimates their behaviors (activities) based on their lifelogs and shows the results to support self-monitoring by themselves.