PURPOSE: To facilitate restitution by forming a paper sheet feeding rotor from a pressure-sensitive electroconductive rubber, converting the change in the length or thickness of a document sheet into an electric signal, and thereby surely sensing double feed of document sheets.

CONSTITUTION: A paper sheet feeding rotor 35 includes a supporting shaft 35a made of electroconductive material, a pressure-sensitive electroconductive rubber 35b installed around the shaft 35a concentrically, and an electroconductive layer 35c arranged around the rubber 35b. With this rotor 35, a sensor circuit 73 is connected which emits different voltage value in compliance with the resistance value of the rubber 35b which varies according to the length or thickness of the document sheet. The sensor circuit 73 senses the voltage value determined by the change in the resistance value of the rotor 35. An A/C converter 74 is equipped with the inverted output function and gives a digital value complying with the change of the voltage value given by the sensor circuit to a control part 61 which controls the whole auto document feeding device 20. The control part 61 judges the document sheet transported condition such as double feed on the basis of the digital value fed from the A/D converter 74.