A disc discriminating device disposed in a disc changer is provided. The disc changer includes at least a tray having a recess. The disc discriminating device includes a sensing circuit and a conductor. The sensing circuit has a first contact and a second contact. The sensing circuit accordingly outputs a signal when the first and second contacts are electrically connected. The conductor has a first end electrically connected to the first contact, a protrusion penetrating an aperture disposed on a sidewall of the recess and protruding to the recess, and a second end interspaced by an interval with the second contact. The protrusion outside the recess is squeezed by a disc when loading into the recess, so that the second end of the conductor is electrically connected to the second contact. The sensing circuit outputs a signal according to the above conduction.