PURPOSE: To eliminate misdetection of paper sheets by allowing a sensor to emit light with the optimum luminous quantity in accordance with a kind of the paper sheets which are detection objects.

CONSTITUTION: A kind of notes, which are detection objects, is set to dip switches 10, 11, 12. A CPU1 detects a preset value of the dip switches 10, 11, 12 and the kind of the paid notes and reads the corresponding luminous quantity of a sensor luminous quantity table, stored in a ROM2, in accordance with this detection to set the luminous quantity to a luminous quantity register 4. Sensors S1 to S8 emit light with the luminous quantity set to the luminous quantity register 4, that is, luminous quantity in accordance with the kind of paper sheets which are detection objects.