To provide a guide device capable of quickly and highly precisely conducting centering of a plate material in a transfer route.

A guide device 1 to guide a plate material W in the longitudinal direction is arranged to a transfer route. The guide device is arranged with a regulating means 4 so that the center of the width direction of the plate material W passes a prescribed position. The regulating means 4 is provided with abutting members 5, 6 to abut on the end edge of the plate material W, pressing members 7, 8 to press the abutting members 5, 6 toward the plate material W and a moving means 9 to move the pressing members 7, 8 in a same reciprocating quantity.