Mouse forced swimming is one of the behavioral depression models and repeated electroconvulsive shock (ECS) treatment has been used to human depression. In order to investigate the mechanism of the anti-depressive effect induced by repeated ECS, we investigated the effect of repeated ECS with the mouse forced swimming model. The 5 times par-day ECS remarkably increased the typical anti-depressive behavior climbing 24 hours after the final treatment. The anti-depressive activity was declined by a dopamine 1 antagonist SCH-23390 at the doses of 1 and 0.1 mg/kg, but not by the other dopamine, serotonin and adrenoceptor antagonists at the dose of 1 mg/kg. The present findings strongly suggest that the late anti-depressive effect of repeated ECS is mediated by the dopamine 1 receptor activity. The present findings will also contribute to the further investigations of the effect of repeat ECS treatments on human depression.