Laser welding method and laser welding jig device

A method for laser welding, the method comprising:

• preparing a pair of workpieces being a pair of plate members respectively having through-holes common in size and shape, which are aligned when the workpieces are overlapped;
• overlapping and placing the pair of workpieces on a base jig having a pin hole aligned with the through-holes;
• preparing a main jig having an opening surrounding the through-holes along a laser welding position surrounding the through-holes outside the laser welding position;
• pressing the main jig against the base jig in a state in which the through-holes are surrounded by the opening;
• positioning the pair of workpieces with each other;
• allowing a displacement force in a direction toward the base jig to act on the main jig to clamp the pair of workpieces;
• preparing a sub-jig having a head and a pin and forming an annular light guiding path guiding a laser beam to the laser welding position located in a gap between the opening of the main jig and the head facing each other in a state in which the pin is inserted into the pin hole;
• inserting the pin into the pin hole through the through-holes of the pair of workpieces placed on the base jig;
• and
• allowing a displacement force in a direction to deepen the insertion of the pin to act on the sub-jig having the pin inserted into the pin hole through the through-holes of the pair of workpieces placed on the base jig until the head abuts against one of the workpieces to clamp the pair of workpieces.