The dynamics of human relationships have made researchers study the factors that affect marriage stability in families. Focus on interpersonal behaviour as a preventive and therapeutic action to decrease marital instability led to the assumption that the characteristics of individual spouses play important roles in the marital outcomes of. However, there is increasing interest in the role of pro-relationship behaviors in repairing and maintaining couples’ relationships. This paper is studying the predictive role of interpersonal forgiveness to decrease marital instability among married women andand men. To reach this purpose three hundreds andand eighty four married people (192 males and 192 females) from five different regions across Qazvin City were selected by multistage cluster sampling. They answered 14-item marital instability scale by Edwards et. al. and 40-item Family Forgiveness Scale of Seif andand Bahari (FFS). The result from administrating the Pearson's correlation test and analysis of stepwise regression showed a strong negative correlation between marital instability with general and and marital forgiveness, also, the negative correlation between marital instability and the stages of forgiveness was observed. The results show that forgiveness in marital relationship generally, and resolution andand understanding as two stages of forgiveness can predict the marital instability of married men. Also, the predictive role of marital forgiveness in the marital instability of married women was confirmed.