An image forming apparatus comprising: an apparatus main body; a plurality of process cartridges detachably mounted in parallel within the apparatus main body, each of the process cartridges comprising a photosensitive drum and a developing roller disposed facing the photosensitive drum; a body frame comprising a plurality of abutment portions (72, 73) disposed to abut the process cartridges, respectively, and a plurality of projecting portions, each projecting portion being associated with a respective one of the process cartridges and projecting in a direction along a rotational axis of the photosensitive drums; a plurality of fixing members, each projecting portion supporting a respective one of the fixing members, each fixing member being associated with a respective one of the process cartridges and being configured to rotate between a locked state in which the fixing member presses the respective process cartridge to abut with the abutment portions (72, 73) and an unlocked state in which the fixing member is spaced apart from the respective process cartridge; a plurality of spacing members, each spacing member being provided on the apparatus main body and being associated with a respective process cartridge, and being moveable between a spacing position at which the spacing member separates the developing roller from the photosensitive drum of the respective process cartridge, and a permissive position at which the spacing member permits the developing roller to contact the photosensitive drum; and a translation member which reciprocates in a single straight line to rotate the fixing members between the locked state and the unlocked state, and to move the spacing members between the spacing position and the permissive position and wherein the translation member further comprises a plurality of spacing surfaces and a plurality of permissive surfaces, each spacing surface associated with a respective one of the spacing members, and each permissive surface associated with a respective one of the spacing members, such that when a spacing member is in the spacing position, the spacing member is brought into contact with the spacing surface of the translation member that is associated with the spacing member, and when the spacing member is in the permissive position, the spacing member is brought into contact with the permissive surface of the translation member that is associated with the spacing member. an apparatus main body; a plurality of process cartridges detachably mounted in parallel within the apparatus main body, each of the process cartridges comprising a photosensitive drum and a developing roller disposed facing the photosensitive drum; a body frame comprising a plurality of abutment portions (72, 73) disposed to abut the process cartridges, respectively, and a plurality of projecting portions, each projecting portion being associated with a respective one of the process cartridges and projecting in a direction along a rotational axis of the photosensitive drums; a plurality of fixing members, each projecting portion supporting a respective one of the fixing members, each fixing member being associated with a respective one of the process cartridges and being configured to rotate between a locked state in which the fixing member presses the respective process cartridge to abut with the abutment portions (72, 73) and an unlocked state in which the fixing member is spaced apart from the respective process cartridge; a plurality of spacing members, each spacing member being provided on the apparatus main body and being associated with a respective process cartridge, and being moveable between a spacing position at which the spacing member separates the developing roller from the photosensitive drum of the respective process cartridge, and a permissive position at which the spacing member permits the developing roller to contact the photosensitive drum; and a translation member which reciprocates in a single straight line to rotate the fixing members between the locked state and the unlocked state, and to move the spacing members between the spacing position and the permissive position and wherein the translation member further comprises a plurality of spacing surfaces and a plurality of permissive surfaces, each spacing surface associated with a respective one of the spacing members, and each permissive surface associated with a respective one of the spacing members, such that when a spacing member is in the spacing position, the spacing member is brought into contact with the spacing surface of the translation member that is associated with the spacing member, and when the spacing member is in the permissive position, the spacing member is brought into contact with the permissive surface of the translation member that is associated with the spacing member.