PURPOSE: To carry precisely an original by providing a sensor for detecting the transparent degree of an original passing through the original supplying side of a platen glass to the original supplying side and arranging a gate part for waiting temporally the original in the front of the sensor.

CONSTITUTION: The automatic original feeding device is constituted of a pair of rotary rolls 3, 4 arranged on the upper position of the platen glass 2 fitted to the upper part of a copying machine body 1, an endless belt 5 wound around the rolls 3, 4 and the gate part 7 positioned on the back of the platen glass 2 in the original 6 carring direction on the upper surface of the copying machine body 1 and waiting the original 6 temporally. A penetration hole 10 is formed on a belt 8 and the sensor 11 consisting of a llght emitting part 11a arragned on the upper part of the belt 5 and a photodetecting part arranged on the lower part detects that the penetration hole 10 has reached a prescribed position.