Depressive mood with apathetic and sadness is one of outcomes addiction treatment and study of decreasing implications has fully necessary. In this research aim was study of Effect of Problem Solving Skill Training on Happiness and Coping in Addicts. In a Quasi-experiment design, after diagnosis of under- treatment addicts with low happiness, by multi stage random cluster sampling 60 subjects assigned to II groups ( experimental & control). Groups before and after intervention and follow up (3month) measured by using Oxford Happiness Inventory & Coping Style questioner. Experimental group instruct by PSCT. Data analyzed by covariance analysis, Pearson r, analysis of variance with repeated measures, dependent t test. There was statistical significant difference between means of two groups in all stages of instruction (happiness: Eta= 24/0), (cognitive style: Eta=0/ 31). In follow-up stage, experimental group show higher happiness and cognitive style. Hypotheses of research accepted. There was relationship between cognitive style (0/57) and Separate Style (0/47) and increasing happiness level. In addition, there was negative meaningful relationship (with 0/99 confidence) between emotional style (-0/41) & avoidant style (-0/35) and decreasing happiness. Happiness and cognitive coping style of experimental group increased after participate to instruction. Using more from cognitive and separate style will result to higher happiness level. Using more from emotional and avoidant style will result to lower happiness level.