Purpose: Current study aimed at exploring the roles of system justification in the effects of consumers’ self-identification with the threatened social in-group on the within-domain versus across-domain consumption. It focused on whether there are positive effects of both of the self-definition and the self-investment on the in-group system justification, and also explored whether the system justification, in turn, could make positive effects on the consumption. Research design, data and methodology: The self-identification was approached in view of self-definition and self-investment when the in-group was threatened by members of their out group. The empirical study was performed with the single factor within-subject design based on the feeling of the consumers’ being threatened when the ingroup was criticized by the others. The in-group threatened was accessed from the memory of each of the undergraduate students participating in the empirical study by asking them to remember the events by which their important in-group was perceived to be threatened in their past life. Questionnaire data collected from the undergraduate students were used to verify research hypotheses by structural equation model in Amos 21.0 program. Results: First, the self-definition positively affected the within-domain versus acrossdomain consumption, but did not affect the in-group system justification. Second, the self-investment positively affected the in-group system justification. Third, the system justification made positive effects on the within-domain versus the across-domain consumption. Therefore, this article could contribute to the development of the theory related to compensatory consumption in the view that there could be the positive mediation roles of system justification in the effects of consumers’ self-investment to their in-group on the within-domain versus across-domain consumption when the in-group is threatened. Conclusions: The results of this study could give managerial implications to brand or product marketing managers. How to vitalize consumers’ self-definition with, and self-investment to, the threatened in-group is at issue to the marketers when consumers’ important in-group was threatened by others. By evoking the in-groupbased self-investment to consumers when the in-group was threatened, the marketers should increase the level of the system justification, and the marketers should promote the consumers to recognize that their products or brands are included into the within-self domain.