PURPOSE: To allow the irradiation of electronic parts with a laser beam without exerting an adverse influence thereon even in the narrow place of the electronic parts by mounting an exit optical part to a movable block in the state in which the optical axis thereof intersects orthogonally with a supporting bar when viewed from the side face, thereby constituting the above device.

CONSTITUTION: A printed circuit board 22 is irradiated with the laser beam 6X from the exit optical part 6 in the state orthogonal with the circuit board, by which a lead 25 is soldered to the circuit patterns. The exit optical part 6 is mounted to the movable block 13 in this case. This movable block 13 is moved within an X-Y plane by a motor, etc., by which the laser beam 6X emitted from the exit optical part 6 is scanned along the length of the supporting bar 9. The laser beam 6X is condensed at a certain contracting angle in the emission of this laser beam and the sectional shape of the supporting bar 9 is determined by nearly the same angle as the condensing angle. Therefore, the electronic part 23, 24 are consequently soldered without interference with the laser beam 6X even if the spacing between these parts is small.