Regulation of anger is fatal for well-being. Recent study has revealed that an effective means of anger regulation depends on interpersonal relationships in that constructive expression has a positive effect on relationship quality in close and equal relationships. To reveal the effective process of anger regulation, the present study focused on attitudinal factors toward emotional expression as determinant factors on constructive anger expression in close relationships. A survey was conducted on romantic adolescent couples and pairs of close friends. Results showed that a negative attitude toward one's emotional expression restrained constructive expression. While another attitudinal factor, expectation of others' emotional expression, had no effect on partners' use of anger regulation tactics, one's cognition of the partners' attitude promoted constructive anger expression. The role of communication for attitude decoding and changeability of attitude were discussed.