A multi-function printer includes an image forming unit and a scanner unit. The image forming unit includes a body casing, a developing unit having a developing roller extending in a lateral direction, a developer cartridge provided on one side of the axis of the developing roller and detachably attached to the body casing, a discharge tray, a side cover, a support unit for supporting the developer cartridge such that the developer cartridge is detachably attached to a front side of the body casing, a sheet feeding tray detachably attachable to the front side of the body casing, and a discharge unit provided on the front side of the body casing and discharging sheet on which an image is formed to the rear side of the body casing. The scanner unit is provided above the image forming unit having a predetermined space opened on the one side therebetween.