PURPOSE: To always allow an image and copy paper to coincide with each other by providing a means for controlling an effective section signal of an image signal in accordance with the case when a document feeding device is used, and the case when it is not used.

CONSTITUTION: When a document feeding device (DF) is not used, a document is butted against a butt reference plate, but when the DF is used, the document is set by shifting it from the butt plate by about 1mm in order that it is not damaged. Therefore, when the DF is not used, 4 is set to a latch 300, and when a counter 301 is counted up by synchronizing with a clock and becomes 5, a comparator 302 outputs HIGH. As a result, a counter 304 starts up-count. To a latch 303, a picture element (n) is set, and when the counter 304 becomes (n) + 1, HIGH is outputted, and a gate 306 outputs an effective section signal VE of an image. When the DF is used, a CPU sets 7 to the latch 300. In such a way, the VE is delayed by three picture elements and rises, and an image becomes that which always coincide with copy paper as to its position.