PURPOSE: To prevent a coil of a coil car from happening of overturning or falling.

CONSTITUTION: In loading a coil 2 carried by a coil car 1 on the mandrel 6a of an uncoiling device 6, the presence/absence of the coil 2 is detected by two photosensors 4, 5 arranged at a prescribed space; electric current is detected on the driving motor 8 of the coil car 1; and the reference current is determined on the coil car at its normal operation. The set upper limit value of a load current is set at 5 to 15% higher level than the reference current of the coil car ; and the overturning of the coil 2 from the coil car 1 is prevented by stopping the coil car 1 when the load current of the coil car is in excess of the set upper limit value of the load current.