An image forming apparatus includes: an image forming section including first and second image forming parts each forming a toner image by using an image forming unit to be mounted, the first and the second image forming parts being inhibited from forming respective toner images if an image forming unit is not mounted to the first image forming part, the first image forming part being allowed to form a toner image if an image forming unit is mounted to the first image forming part while an image forming unit is not mounted to the second image forming part; and a transporting section including first and second receiving parts receiving waste powder discarded by the first and second image forming parts, respectively, and that transports the received waste powder. The second receiving part is provided downstream of the first receiving part in a transporting direction of the waste powder.