The aim of this study was to explore the factors that contribute to cancer patients' motivation for participating in group therapy. Seven cancer patients （mean age = 63; SD = 10.3） who had participated in group therapy were interviewed. Participants were asked about their motivation for participating in group therapy. Through the content analysis of the interviews, seven factors related to motivation for participation in group therapy were identified: the perception of one's own problem and the need to solve it; the lack of and need for social support; the lack of and need for companionship; the ease of participation; the introduction to and recommendation of the program by medical staff; the perception of fl yers; and the interest in and concerns about the program. It's important that medical staff should introduce group therapy to patients who have problems or do not have social support. Therefore, medical staff should not only build good relationships with patients, but also know about support services such as group therapy. In addition, it is also important for medical staff to assess what kind of support patients need, and whether patients need companionship.