PURPOSE: To use one set of a supporting device for welding, and accurately support respective reinforcements used for PC girders of various sections.

CONSTITUTION: A base member 1 for an upper edge and a base member 2 for a lower edge are fittingly provided on guide members 3 so as to relatively approach and separate, and the upper edge base member 1 is provided with a V-shaped reinforcement holding device, and an upper part shrouding reinforcement holding member 5 movable in the lengthwise direction of the guide members. A holding member 6 to hold the upper side of shear reinforcing reinforcement is provided so as to be movable in the perpendicular direction of the guide members, and the lower edge base member 2 is provided with a holding member 7 to hold the lower side of the shear reinforcing reinforcement and a lower part shrouding reinforcement supporting member 8 movable in the perpendicular direction of the guide members.