To appropriately perform the welding connection of a fusible alloy piece between the tips of a lead conductor without losing the mechanical strength of a thin-type fuse in the manufacture of the thin-type fuse.

Holes 10, 10 are punched on an insulating substrate 1 at the position of a scheduled junction of the tip of respective lead conductors 2, 2 and each end of the soluble alloy piece 3. One electrode Pa for welding in a pair of electrodes Pa, Pb for welding is brought into contact with the back of the tip of respective lead conductors 2, 2 through the holes. The other electrode Pb for welding is brought into contact with a flat lead conductor outside the insulating substrate 1. A welding current is allowed to flow via the electrodes Pa, Pb for welding for welding the scheduled junction.