An electrophotographic printer including a pre-erasing unit. The pre-erasing unit includes a pre-erasing lamp to irradiate light, and a pre-transfer erasing lens to induce the light generated from the pre-transfer erasing lamp to the photosensitive drum, movably installed such that it moves to an erasure position at which the pre-transfer erasing lens is close to the photosensitive drum for erasure, and moves to a retracted position spaced apart from the photosensitive drum so as not to interfere therewith when the photosensitive drum unit is being mounted or dismounted. The pre-erasing unit may further include an elastic member to provide elasticity in a direction in which the pre-transfer erasing lens moves to the retracted position.