An image forming apparatus includes: a plurality of image forming units forming an image in the corresponding color by electrophotographic system; a high-voltage power supply circuit capable of generating a bias voltage; and a control unit that controls a first printing mode and a second printing mode, wherein in the second printing mode, the control unit performs such control that the photosensitive bodies provided on the image forming units not used in the second printing mode continuously rotate at a speed lower than a speed in the first printing mode, and/or such control that a bias voltage whose absolute value is less than an absolute value of a bias voltage in the first printing mode is supplied from the high-voltage power supply circuit to the processing components of the same type provided on the image forming units not used in the second printing mode.