PURPOSE: To realize easy operation and to form preliminary solder of an accurate solder amount by punching a solder piece out of a solder sheet, by opposing it to a wiring substrate using a heat resistant adhesive tape as a carrier and by heating it.

CONSTITUTION: A heat resistant adhesive tape 16 which is supported by a frame 15 is arranged with its adhesive side up between a base 12 and a female mold 14. A solder sheet 17 is mounted on the female mold 14; the sheet 17 is punched out by a punch 13a; and a solder piece 17a is bonded to a tape 16. The tape 16 which holds the piece 17a by bonding is set to a jig so that the piece 17a is opposed to a pattern 20 to form a preliminary solder of a wiring substrate 19 which is supported by a jig 18. A keep plate 21 is mounted on it. The jig 18 and the substrate 19 are positioned by a recessed part; the tape 16 is positioned by a guide hole provided to the frame 15 and a positioning pin 22; and the piece 17a is heated. Through heating, the piece 17a attaches to the pattern 20 of the substrate 19 and forms preliminary solder.