The purposes of this study are to investigate the effects of mood and objective self-awareness on the helping intention and explicit helping behavior. This research consists of 3 experiments. In Experiment 1, a 2 × 4 factorial design with two variations in mood (positive and negative) and four types of self-awareness (high, low, no, and interrupted) was employed. The mood variations were induced with music. The dependent variables were helping intention and helping behavior (signing a petition and working as a volunteer). No main effects or interaction effects were found. In Experiment 2, the mood was induced through a recall task. A 2 × 2 factorial design with 2 mood states (happy and sad) and 2 self-awareness levels (high and low) was used. The dependent variable is the intention to help another. Neither main effects nor interaction effect was found from the results of a two-way ANOVA. In Experiment 3, the mood was induced with music used in Experiment 1. But the dependent variable was measured differently. The numbers of characters the subjects agreed to write for the experimenter as a help was operationalized as the degree of helping behavior. A 2 × 2 factorial design with 2 mood states (positive and negative) and 2 self-awareness levels (awareness and no awareness) was used. The ANOVA revealed main effects for mood states and self-awareness. The interaction of mood and self-awareness was also found: The different effects of mood on helping behavior were found only in no self-awareness condition.