Private self-consciousness is classified into self-rumination and self-reflection according to its motivation. Self-rumination is considered maladaptive while self-reflection is considered adaptive for mental health. This study examined which kinds of interpersonal stress events affect self-rumination and self-reflection. We conducted a longitudinal study with undergraduate students. Hierarchical multiple regression analysis showed that the level of self-rumination was increased by events which relate to an inferiority complex. The levels of self-reflection were not affected by any kind of events. This result suggests that interventions for inferiority complex could be effective for reducing the level of self-rumination.