PURPOSE: To perform plural detections with a single of detecting device, by constituting the device such that a reflex photosensor and reflecting means are provided by interposing a transfer paper-conveying path between a cassette and resist roller and the reflecting means is separably placed from a reflective position at insertion of the cassette.

CONSTITUTION: When a cassette 20 is not inserted, a reflecting means 12 is placed in a reflective position by a spring 14. Accordingly, a reflex photosensor 10 is turned on to discriminate the cassette 20 not inserted. The cassette 20 is inserted, and the reflecting means 12 is turned counter clockwise by a pressing member 22 and separably placed from the reflective position, then the photosensor 10 is turned off, thus the cassette 20 can be detected its mounting. If a time from a start of rotation of a paper feed roller 4 to detection of the point end of paper 24, or a time from rotation of resist rollers 16, 18 to detection of the rear end of the paper 24, are each out of a prescribed time, it is detected that there is no paper or jam of paper is happened. In this way, constitution can be simplified and maintenance work can be easily performed.