1. A paper discriminating apparatus wherein a paper conveyed in a predetermined conveyance direction is scanned in conjunction with a conveyance of the paper by a plurality of sensor devices arranged in an arrangement direction intersecting the predetermined conveyance direction to detect areas of the paper each being longitudinal with respect to the conveyance direction by associated sensor devices, respectively, and the paper is discriminated in accordance with image data obtained through a detection of the paper, said paper discriminating apparatus comprising: a line sensor in which a plurality of sensor devices are arranged in the arrangement direction in such a manner that a non-sensed area on the paper, which is not detected by any of the sensor devices, is formed between two sensed areas to be detected by two adjacent sensor devices; a data correction unit generating image data associated with the non-sensed area on the paper; a dictionary data unit storing dictionary data associated with a full range of the paper, the dictionary data being reference data for discrimination of the paper; and a dictionary comparing unit comparing image data associated with the full range of the paper, the data comprising image data as to the sensed areas obtained by said line sensor and image data as to the non-sensed areas obtained by said data correction unit, with the dictionary data stored in said dictionary data unit, and thereby discriminating the paper detected by said line sensor.