An image forming apparatus includes a plurality of developing portions capable of developing electrostatic latent images formed on an image bearing member, and a control portion for executing preparation operations for developing operations with respect to each of the plurality of developing portions. The image forming apparatus has a first mode for conducting image formation by use of the plurality of developing portions, and a second mode for conducting the image formation by use of only a predetermined developing portion in the plurality of developing portions. The preparation operations for the predetermined developing portion are executed earlier than the preparation operations of the developing portions other than the predetermined developing portion in the plurality of developing portions, and the image formation in the second mode can be done earlier than the first mode.