To provide a ground connection device for electric apparatus which permits complete ground connection in conformity with polarity to be conducted automatically.

In this electric apparatus 2 which receives power supply from a commercial power supply 1 with one wiring 1a grounded, a detection current limit resistor (R1) and a circuit switching means (RY1) are provided for one side 2a of power receiving wiring on product primary side, and a detection current limit resistor (R2) and a circuit switching means (RY2) are provided for the other side 2b. Polarity determination circuits 3a, 3b detecting current (I1 or I2) in a closed condition of the circuit switching means (RY1), (RY2) is provided for polarity determination. A switching means 5 controlling operation by a controlling means 4 so that the ground (G) of a ground terminal connection circuit may be connected to one wiring 1a according to the determination output results.