FIELD: authenticating coins including conductance measurement between first and second parts of coin. SUBSTANCE: device has coin channel 3 for passing coin 5 that has first and second parts 13a and 13b made of different metals and/or metal alloys, coil means 1a, 1b disposed close to coin channel, electric means 7 for feeding time-varying signal to coil means, and detection means 9 for detecting eddy currents excited in coin by coil means. Coil means 1a, 1b are designed to excite eddy-current circuit 27 in coin 5 which crosses link 11 between first and second parts 13a, 13b of coin in predetermined area 25. EFFECT: enhanced precision of detecting conductance or resistance at link between first and second parts of coin. 11 cl, 3 dwg
