PURPOSE: To perform inline respective steps for inserting, soldering and cleaning a printed circuit board and using in common a pallet formed of a material to which solder is hardly stickable by holding the printed circuit board by said pallet and conveying the same.

CONSTITUTION: A printed circuit board 25 is held to a pallet base by positioning plates 5, 7 provided to a pallet 1 and a positioning plate 6. Retaining caps 9, 10 are closed and the board 25 is clamped by work holders 15, 23 via springs 16, 24. The bottom surface is held by a work retainer 19. Such pallet 1 is conveyed to a line consisting of a solder tank and a cleaning tank by a conveyor. The material to which solder is hardly stickable is used for the material of the pallet base 1. The need for masking the board 25 in the stage of soldering is eliminated by such mechanism. Since there is no need for removing the board 25 in the midway of the step, the step is reduced.