PURPOSE: To copy images on two originals to one copy paper together in different colors by adding a composite copying unit which has an original conveyance part, fixed light source, mirror, and lens to a two color copying machine.

CONSTITUTION: The composite copying unit 50 is provided additionally to the two color copying machine which has the 1st photosensitive drum 8 and the 2nd photosensitive drum 10; when a composite copy is taken, one original is placed on an original placing platen 1, another original is set on an original feed table 51, and the exposure scanning by the light source 2 and the original conveyance by a feed roller couple 542 are started at prescribed timing. Consequently, an image on the original on the platen 1 is developed in, for example, black on the 2nd photosensitive drum 10 and an image on the conveyed original is lighted by the fixed light source 55 and developed in, for example, red on the 1st photosensitive drum 10. Thus, the images of the two originals are copied together to one copy paper as the different-color images.