The purpose of this study was to investigate the functions of involuntary memory in the course of daily life. The participant was the author, a 39-year-old male at the time when the record of involuntary memories was begun. When an autobiographical memory occurred spontaneously, the participant would record the contents of that memory and the circumstances surrounding its occurrence, such as the triggered cues for the remembered event and the participant's activity and mood at the time. Over a period of four and a half years, involuntary memories of 184 events were collected. The results suggest four functions of involuntary memory: (1) confirmation of one's existence at a given time in one's life history; (2) confirmation of one's own psychological traits; (3) confirmation of one's relationship to others; and (4) the direction or regulation of one's behavior. One of the main functions of involuntary memory may be to provide one with the opportunity for recognition of the individual's stable beliefs and behavior, that is, the sense of self-continuity.