An image forming apparatus includes an opening/closing mechanism for opening a lid member when a toner collecting portion including a waste toner bottle and the lid member for the waste toner bottle is mounted into an apparatus main body while closing the lid member when the toner collecting portion is removed from the apparatus main body. The opening/closing mechanism includes a first contact portion provided in a toner discharging portion for discharging toner for rotating the lid member in a first direction by coming into contact with the lid member when the toner collecting portion is mounted into the apparatus main body, and a second contact portion mounted in the apparatus main body for rotating the lid member in a second direction by coming into contact with the lid member when the toner collecting portion is removed from the apparatus main body.