PURPOSE: To improve accuracy by obtaining a deviation in relation to a target position from a distance to a pallet carry-in direction front end surface and from each distance to a coil end surface and to a pallet end surface, measured in the right angle direction to this distance to the pallet carry-in direction front end surface, in a detecting device of a coil on a pallet of a storage yard or the like.

CONSTITUTION: A pallet 20, on which coils 10, 10 are parallelly mounted, is carried into a storage yard in a direction of a white arrow mark. A distance A to a front end surface 21 of the pallet 20 in the carry-in direction is measured by the first distance meter 30. A distance C to an end surface of the coil 10 and a distance B to a side surface 22 of the pallet 20, in the side surface of the pallet 20 along the carry-in direction, are measured by the second distance meters 40, 40. These distance meters 40 are vertically moved on mounting bases 41 to perform measurement. A deviation in relation to a target storage position is calculated by an arithmetic device 50 so as to obtain a plane position of the coil based on a measured result of these distance meters 30, 40, 40.