PURPOSE: To automatically recognize the size and near-end of a recording sheet correctly by detecting the size of a recording sheet by a sensor disposed opposite to each near-end mark of recording sheets of every sizes.

CONSTITUTION: A black near-end mark 1a is printed on a side portion of the trailing end portion of a recording sheet 1, and a black near-end mark 2a is printed on a side portion of the trailing end portion of the trailing end portion of a recording sheet 2, the mark 2a being positioned in such a manner not to lie upon the mark 1a. A recognition system includes a recording rubber roller 3 for feeding recording sheets 1, 2 of each size, with the sheets in opposition to a recording electrode 4, a sensor 5 disposed corresponding to the near-end mark 1a of B4 size recording sheet 1, and a sensor 6 disposed corresponding to the near- end mark 2a of A4 size recording sheet 2. The respective sensors 5, 6 are formed in a light reflection type having a projector and a photo detecting device. The above system further includes means for obtaining a size output of each recording sheet and a mark read output according to the detection order of detection signals of the photosensors.