PURPOSE: To prevent breakage of a PC steel bar by arranging resin or resin mixed material of coated layer at periphery of each weld zone between the PC steel bar group and iron wire for forming an iron-reinforcing basket.

CONSTITUTION: The PC steel bar group 1 lowering sensibility to delayed fracture by increasing Si is set at almost the prescribed interval on interval on the circle, and the iron wire 2 is wound on the outer periphery. Contact part between this PC steel bar 1 and the iron wire 2 is spot-welded, but this weld zone arranges the coating layer 3 with the resin at the periphery. Forming position of this layer is made to the weld zone and the outer periphery of PC steel bar 1 contacting with the weld zone. Forming method of the coating layer 3 is executed with spraying or coating. As the PC steel bar at the welding position is accompanied with raising of temp., by executing the coating with thermosetting resin of epoxy resin, etc., while this temp. is high, the coating layer having higher adhesion is efficiently formed. By this method, the delayed fracture characteristic can be efficiently and easily prevented.