There is provided an image forming apparatus which includes an body, a feeding tray, a pickup roller, a roller supporting mechanism which supports the pickup roller, a pressing plate which elevates a sheet at the time of sheet feeding, an ascending mechanism which makes the pressing plate ascent, a drive source which is provided to the body, a drive gear, a one-way clutch mechanism which transmits the driving force to the ascending mechanism, a coupling member which moves in conjunction with a vertical movement of the pickup roller, and a transmission-state switching mechanism which is engaged with the coupling member, and which allows or inhibits the transmission of the driving force from the drive gear to the one-way clutch mechanism, in accordance with the movement of the coupling member.