The purpose of this study was to investigate the relationships between the attachment, optimism, and psychological well-being of adolescents` parents and also the mediating effects of optimism on the relationships between parental attachment and psychological well-being in adolescents. For the study, 554 middle school students completed survey packets that included the Inventory of Parents and Peer Attachment (Revised), Reevaluation of Life Orientation Test, and the Psychological Well-Being Scale. The results of this study were as follows: First, the parental attachment had significant effects on the psychological well-being and optimism of adolescents. Second, when adolescents felt high optimism it was found to correlate to high psychological well-being. Third, as a result of verifying the mediating effects of optimism on the relationship between parental attachment and the psychological well-being of adolescents, optimism was found to have mediated in this relationship. Fourth, paternal attachment was found to have higher effectiveness than maternal attachment in the psychological well-being of adolescents. It is meaningful that the baseline data was offered, which can contribute to improving adolescents` psychological well-being.