PURPOSE: To provide an inexpensive small-size leak alarm device with a simple structure capable of detecting a leak current flowing in a plurality of phase distribution lines.

CONSTITUTION: A leak alarm device has a detecting circuit 4A for detecting a ground current flowing in a single phase distribution line and a detecting circuit 4B for detecting a ground current flowing in a three-phase distribution line. The device is further formed of a display circuit 5 having a thyristor 56A continued in replay to the output of the detecting circuit 4A, a thyristor 56B continued in replay to the output of the detecting circuit 4B, a leak indicator lamp 52A lighted by the continuation of the thyristor 56A, and a leak indicator lamp 52B lighted by the continuation of the thyristor 56B.