PURPOSE: To maintain the positioning accuracy of a conveyed object in a conveyor with simple constitution so as to avoid the temporary stop of the conveyor.

CONSTITUTION: In the case of a pitch-fed bearer plate 58 being dislocated in relation to a positioning device, a pair of bearer guide pieces 36 push a tapered face 56 in the side wall 54 of a workpiece bearer 40 by a tapered face 37 in the advance process so as to make external force act upon the workpiece bearer 40 in the direction shown by an arrow mark X0. The workpiece bearer 40 is thereby moved in the direction of the arrow mark X0 practically by itself by the external force. A pair of bearer guide pieces 36 are then engaged with the side walls 52, 54 of the workpiece bearer 40 in the advance process, and the workpiece bearer 40 is guided into the positioning position of a work area.