PURPOSE: To reduce power loss at the time of limiting a current by connecting a normally closed contact in series with a plurality of series first superconducting coils wound noninductively, and connecting a second conductive superconducting coil having a higher critical current value than that of the first coil in parallel.

CONSTITUTION: A normally closed contact switch 2, a current limiter 3 and a load 9 are connected in series with an AC power source 1. In the limiter 3, a current limiting coil 5 made of an inductive superconducting coil having a predetermined critical current (IC2) is wound inside a common spool 4. A heat insulating plate 7 is held at the outside, a plurality of noninductively wound coils 6a-6c are connected in series in a multilayer state to form a trigger coil. The coils 6a-6c are formed by winding superconducting materials set lower in critical current (IC1) than the IC2 and connecting a switch 8 in series. When the critical current IC1 exceeds by the overcurrent of the load 9, the trigger coil is quenched to show a high resistance, the current is commutated to the coil 5, thereby rapidly opening the switch 2 by the voltage of both ends. Thus, the power loss at the time of limiting the current is reduced.