To obtain a GPS receiving system by which, when a trouble is generated in an apparatus using the GPS receiving system, an abnormal part can be discriminated simply in the installation site of the GPS receiving system without performing a dismantling operation, a special inspection operation or the like.

In this GPS receiving system as a separate body, an antenna part 1 which comprises an antenna part 2 used to receive radio wave signals from a plurality of satellites for a GPS and which comprises an amplifier for the received signals is provided, a receiver 5 which demodulates the received signals, which performs a positioning and computing operation and which outputs position information is provided, and the antenna part 1 and the receiver 5 are connected by a cable 8. In the GPS receiving system, the outer face of the antenna part 1 is provided with an LED 4a, and the LED 4a is turned on when a current flows to the amplifier in the antenna part 1.