An image forming apparatus includes a rotation driving source, a black developing unit, a color developing unit, a first gear, a second gear, a development drive transmission mechanism and a switching mechanism. The development drive transmission mechanism includes a first intermediate gear and a second intermediate gear. The switching mechanism includes a linear cam member configured to move linearly and to move the first intermediate gear and the second intermediate gear such that: in the first mode, the first gear engages the first intermediate gear and the second gear engages the second intermediate gear; in the second mode, the first gear engages the first intermediate gear and the second gear is disengaged from the second intermediate gear; in the third mode, the first gear is disengaged from the first intermediate gear.