[영문]Total fertility declined in states that introduced unilateral divorce, which makes dissolution of marriage easier. Also the ratio of out-of-wedlock fertility over total declined. We suggest an explanation (and provide supportive evidence for it) based upon the effect of divorce laws on the probability of entering and exiting marriage. Women planning to have children marry more easily with an easier qqqquot;exit optionqqqquot; from marriage. Thus, more children are born in the first years of marriage, while the total marital fertility does not change, probably as a result of an increase in divorces and marital instability.