Beam welding apparatus and beam welding method

A beam welding method that welds a housing and transparent cover of a vehicular lighting device via beam welding, said method comprising steps of:

• overlaying the welding part of the transparent cover on the welding part of the housing and, arranging a cover fixing jig including a beam transmitting part on the transparent cover, and pressing the transparent cover toward the housing;
• and
• irradiating beams onto the welding part of the housing through the beam transmitting part and the transparent cover to excite and heat the welding part of the housing via irradiation of the beams, heating also the welding part of the transparent cover via the heating in order to join the two welding parts in a compatibilized state;
• characterized in that residual beams obtained after unnecessary luminous flux are shielded by a shielding part formed in the beam transmitting part among the beams irradiated by the beam irradiating part is irradiated onto the welding part of the housing.