To provide a non-contact power transmission device which certifies that a portable device is correctly placed on a supporting stand, avoids power transmission at abnormal time and prevents heat generation by a metal piece such as coin.

The transmission device includes a charging device body 10 incorporating a charging transmitting coil L1, the portable device 20 incorporating a charging receiving coil L2 and the supporting stand 11 formed in a part of a main body for attachably/detachably loading the portable device. The device is constituted of the portable device 20 having a permanent magnet 4b and an infrared light emitting element 3b, and the supporting stand 11 where a magnetic field detecting element 4a is arranged in a position confronted with the permanent magnet 4b and a light receiving element 3a in a position confronted with the infrared light emitting element 3b. When the magnetic field detecting element 4a detects a magnetic field of the permanent magnet 4b and the light receiving element 3a detects light from the infrared light emitting element 3b, namely when the portable device is certified to be correctly placed in a prescribed position of the supporting stand, power is transmitted to the receiving coil from the transmitting coil.

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