To optically detect with ease and accuracy a projection or a recessed pattern (an emboss) present at a predetermined position on a normal coin.

This apparatus includes an optical means 10 for applying light spots La and Lb to the projection or the recessed pattern 1a present at the predetermined position on the coin 1 inserted and for receiving the reflected light spots La and Lb, and a determining means for determining whether or not the projection or the recessed pattern 1a exists in the predetermined position on the inserted coin 1 according to the received signals of the light spots La and Lb.