PURPOSE: To realize a counter which can count the number of pieces of paper sheets at a high speed and exactly by a simple operation.

CONSTITUTION: The optical counter 50 is provided with a receiver (hopper) 62 for an object to be measured, for superposing and mounting a matter 60 to be measured, a fixing stand 63 for fixing the matter 60 to be measured, and a line image sensor 64 which is mounted so as to be opposed to the matter 60 to be measured, along the edge of the matter 60 to be measured, superposed and fixed onto the receiver 62 for the matter to be measured, and detects optical information from the edge of the matter 60 to be measured. Also, the receiver 62 for the matter to be measured holds, superposes and fixes the matter 60 to be measured by the fixing stand 63 for sliding on the receiver 62 for the matter to be measured, and detects optical information by the line image sensor 64 provided so as to be opposed to the matter 60 to be measured, along the edge of the matter 60 to be measured, superposed and fixed on the receiver 62 for the matter to be measured.