An image forming apparatus includes a casing, a photosensitive drum, an exposure head, a developing cartridge, and a light shielding member. The photosensitive drum is rotatably disposed inside the casing. The exposure head is configured to expose the peripheral surface of the photosensitive drum to light. The developing cartridge includes a developing roller configured to supply the developer onto the peripheral surface of the photosensitive drum. The developing cartridge is mountable in and dismountable from the casing. The developing cartridge has an uppermost point and is disposed beneath the exposure head when mounted in the casing. The light shielding member has a first portion disposed between the exposure head and the developing roller and intersecting with an imaginary plane defined by inclusion of the axial line of the photosensitive drum and the uppermost point of the developing cartridge.