To provide an electric leak checker capable of reducing the cost and the outer shape dimension of a case by reducing the number of switches by one, and preventing failure of power input by switching of sensitivity current which turns the power source ON.

The electric leak checker 1 comprises a zero phase transformer 3 detecting leak current carried to a cable way 2, an electric leak determination circuit 5 determining electric leak in a case that the output current of the transformer 3 exceeds a regulated value; a transistor 6 which is on by an output signal of the circuit 5; and an electric leak indicator 7 carrying current by ON of the transistor 6 to perform a display, and a DC power source 8 for driving the circuit 5 and the indicator 7. The ON/OFF of the DC power source 8 and the sensitivity of leak current to be detected by the transformer 3 are switched by one change-over switch 10, and the sensitivity of leak current is increased stepwise by successive switching from the OFF position.