This study examined how environmental change and others' behavior affected cooperative behavior and solution preference of the person in social dilemma situation. Participants in two experiments played an “environment game, ” in which gradual pollution in environment and reduction in profit rate were simulated. Information on behavior of other players was manipulated; in “free rider” condition, one person was an extreme free rider, and the others were cooperative; in “loafing” condition, everyone loafed. In both experiments, “Bad Apple Effect” was not observed clearly, and cooperative behavior increased as environmental pollution worsened. In Experiment 2, there was no main effect of others' behavior on solution preference. However, significant correlations were found among solution preference, motivation to control others' behavior, and perceived seriousness of the situation, only when an extreme free rider was among them.