PURPOSE: To bond surely and securely a fine wire by pressing and fitting the fine wire into the fine-wire fitting part provided to a material to be joined and irradiating an energy beam like a spot to both members.

CONSTITUTION: A square groove 2 is provided to a terminal 1 and the fine wire 3 is pressed and fitted into the groove 2 by means of a press-fitting jig, etc. The wire 3 is so positioned that the end thereof do not jump out of the groove 2. The laser beam B is irradiated like a spot to both members in this state. The spot center of the beam B is made coincident with the center of the wire 3 to prevent the molten state from deviating from the axis of the wire 3. The beam B joins instantaneously the wire 3 and the terminal 1 and therefore the joining in the atm. is made possible. Since the end of the terminal 1 and the boundary between the molten part and unmolten part is spaced by ≥0.5 times the diameter of the wire 3, the wire 3 is surely and securely joined and the automatic joining operation is made possible.