An image forming apparatus, comprising: an image forming part to form an image on a recording medium; a sheet feeder to feed the recording medium to the image forming part; a drawer unit withdrawably installable in the image forming apparatus disposed within the image forming part during operation of image forming apparatus; and a front cover mounted on the drawer unit, the front cover being closably openable relative to the image forming apparatus with movement of the drawer unit, a lock mechanism to switch the front cover, in a state in which the front cover is closed relative to the image forming apparatus, between a locked state that immobilizes the front cover and an unlocked state that allows the front cover to move, the lock mechanism comprising a stationary member fixed to the image forming apparatus; an interlock switch to control operation of the image forming part; characterized in that the lock mechanism further comprises a pick rotatably provided to the front cover, a position of the pick being switched by rotation thereof, in a state in which the front cover is closed, between a locked position in which the pick engages the stationary member to switch the state of the front cover to the locked state and an unlocked position in which the pick is disengaged from the stationary member to switch the state of the front cover to the unlocked state; and an operating member (65, 67) that rotates the pick between the locked position and the unlocked position, and the apparatus further comprises a switching member provided to one of the drawer unit and the front cover, the switching member turning on the interlock switch when the lock mechanism is in the locked state and turning off the interlock switch when the lock mechanism is in the unlocked state. an image forming part to form an image on a recording medium; a sheet feeder to feed the recording medium to the image forming part; a drawer unit withdrawably installable in the image forming apparatus disposed within the image forming part during operation of image forming apparatus; and a front cover mounted on the drawer unit, the front cover being closably openable relative to the image forming apparatus with movement of the drawer unit, a lock mechanism to switch the front cover, in a state in which the front cover is closed relative to the image forming apparatus, between a locked state that immobilizes the front cover and an unlocked state that allows the front cover to move, the lock mechanism comprising a stationary member fixed to the image forming apparatus; an interlock switch to control operation of the image forming part; characterized in that the lock mechanism further comprises a pick rotatably provided to the front cover, a position of the pick being switched by rotation thereof, in a state in which the front cover is closed, between a locked position in which the pick engages the stationary member to switch the state of the front cover to the locked state and an unlocked position in which the pick is disengaged from the stationary member to switch the state of the front cover to the unlocked state; and an operating member (65, 67) that rotates the pick between the locked position and the unlocked position, and the apparatus further comprises a switching member provided to one of the drawer unit and the front cover, the switching member turning on the interlock switch when the lock mechanism is in the locked state and turning off the interlock switch when the lock mechanism is in the unlocked state.