PURPOSE: To minimize the amount of movement of a color selecting mechanism by controlling the welding sequence and welding strength, and by matching the positional relationship between the panel after welding and the color selecting mechanism to the positional relationship before welding.

CONSTITUTION: No.1WNo.3 supporting springs 7AW7C fitted on a color selecting mechanism 5 are engaged with No.1WNo.3 metal pins 9AW9C installed in the center of an edge member of a panel 1P and the left and right members adjoining thereto. To laser weld the metal pins 9AW9C with corresponding supporting springs 7AW7C, a plurality of welding points of No.1 metal pin 9A with No.1 supporting spring 7A are welded in a certain sequence. Thereafter a plurality of welding points of No.2 metal pin 9B with No.2 supporting spring 7B and those No.3 metal pin 9C with No.3 supporting spring 7C are welded alternately, and the welding strength is controlled as each welding point require. This minimizes dislocation of the final panel after completion of all welding from the color selecting mechanism.