A developing-equipment switching apparatus is provided with a rotary retainer 23 for holding a plurality of developing implements 23, a driving motor 24, control means 28 for controlling the rotation of the driving motor 24, a primary drive transmission member 25 which is anchored to the rotary shaft 24a of the driving motor, and a secondary drive transmission member 23b which is anchored to the rotary retainer 23, so that the developing implements 21 are switched from one to another by transmitting the torque of the driving motor 24 to the rotary retainer 23 via the primary drive transmission member 25 and the secondary drive transmission member 23b to rotate the rotary retainer, wherein the control means 28 causes the driving motor 24 to rotate every integral number of times and sets the rotational ratio between the primary drive transmission member 25 and the secondary drive transmission member 23b in such a way that the rotary retainer 23 rotates by a set angle between the adjoining developing implements 21 when the driving motor 24 is rotated the integral number of times.