Background: Exercise training (ET) after coronary stenting is considered to have a risk of stent thrombosis (ST). The present study investigated whether ET increases the incidence of ST in patients undergoing coronary stenting. Methods and Results: The current study was a prospective observational study. We enrolled 3,672 patients who underwent successful coronary stenting. Patients decided whether to participate in exercise and were divided into an ET group (n=1,592) and a control group (n=2,080). The primary endpoint was the incidence of ST. Secondary endpoints were major adverse cardiovascular events (MACE: death, myocardial infarction, and stroke) and unscheduled hospital visits for angina. The incidence of ST and MACE were similar in both groups (1.8% vs. 2.0%, P=0.73, 14.9% vs. 15.0%, P=0.97, respectively). Unscheduled hospital visits were significantly lower in the ET group (20.2% vs. 27.2%, P<0.0001). After adjusting for baselines, the ET group had no significant increase in ST (hazard ratio (HR) 0.86, adjusted P=0.56) and MACE (HR 0.98, adjusted P=0.83). The ET was effective to prevent an unscheduled hospital visits for worsening angina (HR 0.67, adjusted P<0.0001). Conclusions: Moderate ET after successful coronary stenting does not increase the incidence of ST and MACE, and was effective in reducing unscheduled hospital visits for angina. (Circ J 2011; 75: 2379-2386)