PURPOSE: To surely detect a forged coin by applying a pressing force which is large enough to deform the forged coin to the surface of a coin conveyed in a coin passage and detecting the difference in movement quantities between a genuine coin and the forged coin.

CONSTITUTION: A coin which is sent downstream from a conveyor belt moves onto a couple of driving rollers 42 and is clamped by a pressure roller 45, both the sides of the reverse surface of the coin are mounted on the driving rollers 42, and the pressure roller 45 abuts on the center of the top surface of the coin. When the coin is genuine, the coin never deforms with the pressing force applied from the pressure roller 45, so the movement quantity of a vertical moving frame 46 pressed up through the pressure roller 45 is large, a swing arm 52 swings large, and the depression of a detecting element 61 by a detection lever 62 is released to turn off a microswitch 60, thereby deciding that the coin is genuine. If the coin is forged, on the other hand, the coin curves and deforms by being pressed by the pressure roller 45, so the movement quantity of the vertical moving frame 46 is small and the depression of the detecting element 61 by the detection lever 62 is not released.