Abstract: An apparatus for testing the authenticity of coins, tokens or other flat metal articles includes a coin passage with a lower and an upper side wall. A coin moves in a condition of bearing against the lower side wall along the coin passage past at least one inductive measuring element having a coil (S). The coil (S) can be fed with a first current (I.sub.1) from a first current of voltage source (19) and a second current (I.sub.2) from a second current or voltage source (21). A capacitive element (C.sub.1) is connected between the coil (S) and the first current or voltage source (19) so that the coil(S) and the capacitive element (C.sub.1) form an impedance (Z.sub.1). The phase shift (.phi..sub.1) between the first current (I.sub.1) and the voltage across the impedance (Z.sub.1) serves as a criterion for acceptance or rejection of the coin.