PURPOSE: To enhance the efficiency of double side copying and to improve the productivity by storing both of front and rear sides of an original respectively to a prescribed storage area and forming the image based on the stored original picture data.

CONSTITUTION: An original rear detection unit SIRU selects either the both side read mode or the one-side read mode based on the result of detection a rear of an original. When the double side read mode is selected, an original is fed to a picture read section IRU of a picture read section 40 and the picture on the front side is sequentially read. Succeedingly the rear picture of the original is read via a switch-back section SB and a re-feed paper path 58. After the front and rear side picture data of the original to be read are stored in a prescribed storage area of a RAM respectively, the data are outputted to an image forming section 1. Thus, a forming section 2 able to form the picture on both sides of the paper forms the picture on both front and rear sides of paper. Thus, the double side copying efficiency is improved.