To reduce cost and equipment size of a ground-fault directional relay by enabling a relay to function as two conventional relays, by providing ground-fault detecting circuits which are respectively operated with two different directions of ground-fault currents and to which operating time limits can beat separately.

Ground-fault detecting circuits 1A and 1B of a ground-fault directional relay are composed of the circuits of an ordinary ground-fault directional relay and their directional characteristics in different directions are realized by connecting transformers to the circuits 1A and 1B. Namely, a transformer 2 and a voltage transformer 3 are connected to the circuits 1A and 1B so that the circuit 1A may operate in the flowing-in direction of the electric current from a power source A, and the circuit 1B may operate in the flowing-in direction of the electric current from another power source B. In addition, the relay is provided with output contacts DGAC and DGBC which are closed when the circuits 1A and 1B operate. The operating time limits of the circuit 1A and 1B are separately set similarly to an ordinary ground-fault directional relay. Therefore, the cost and equipment size of the ground-fault directional relay can be reduced, because the relay functions as two conventional ground-fault directional relays and the relay required only one zero-phase current transformer.