Moral condemnation may guide individuals into choosing the same side as other bystanders in disputes. If this is the case, people would condemn an actor more strongly when they are conscious of other bystanders than when they are not. In this study, participants were asked to judge the unacceptability of theft and deception in hypothetical situations. Unacceptability (condemnation) scores were compared between participants in two groups: those who provided only their scores and those who estimated others’ scores before providing their own. The results revealed that older participants were less willing to accept immoral behaviors than younger participants. When conscious of others’ judgments, younger participants tended to reduce their condemnation while older participants tended to increase their condemnation. Additionally, condemnation was stronger in females than males. The results support the hypothesis that those who are more likely to avoid direct and physical competition are more willing to condemn, and that moral condemnation functions as a “flag”.