A multicolor developing device having a plurality of developing mechanisms for executing developing with differrent colors. The developing device includes a stationary frame member, a movable frame member mounted on the stationary frame member to reciprocally move in a predetermined direction, and a moving device for reciprocally moving the movable frame member. The plurality of developing mechanisms are mounted on the movable frame member and maintaining a distance in the said predetermined direction. Any one of the plurality of developing mechanisms is selectively positioned at a developing zone depending on the movement of the movable frame member. The moving device includes a screw device having a threaded shaft extending in the predetermined direction and a nut engaged with the threaded shaft, a stepping motor for rotating the threaded shaft, and a nonexcited operation-type electromagnetic brake. A pair of racks are disposed on the stationary frame member and maintain a distance in the lateral direction, and the movable frame member is provided with a rotary shaft extending in the lateral direction and a pair of pinions fitted to the rotary shaft, the pair of pinions being engaged with the pair of racks. Each of the developing mechanisms is provided with a pair of distance-setting rollers which are brought into resilient contact with a rotary drum in order to accomplish the positioning of the developing mechanism relative to the rotary drum.