Thank you for your reply.
I just made the autosave check disable but still OnSave events are not fired.
By the way, I traced JavaScript events and found an event which is called after closing a Opportunity record.
The code block below works fine, although it's not a supported way.
var original = Mscrm.CommandBarActions.performActionAfterOpportunityClose;
Mscrm.CommandBarActions.performActionAfterOpportunityClose = function(returnValue){
//write your custom code
original(returnValue)
}
Taichi,Sato