Most researches about consumer regret focus on action regret which is generated after purchasing, while less attention is paid to inaction regret which is generated after missing a purchase. Some researchers have shown that the consumer who experienced inaction regret is valuable, because his purchase intention is similar to satisfied consumer’s, even higher than the latter. This research shows that the limitation of purchase opportunities is a main cause of inaction regret. It has a positive effect on the inaction regret. Endowment effect is a significant mechanism. When consumers miss purchasing, there will be a strong endowment effect if the purchase opportunities are limited. Then endowment effect has a positive influence on inaction regret. Moreover, the effect of limitation of purchase opportunities on endowment effect is moderated by product category. These hypotheses are demonstrated through two behavioral experiments.