To provide a spark plug for internal combustion engine having a high jointing strength between a spark wear resistant electrode material and an outer electrode, and its manufacturing method.

A spark wear resistant electrode material 18 of chip shape is installed on an installation face 16b of the outer electrode 16 in the state before the outer electrode 16 is bent and a spark discharge gap is formed, and pulse YAG laser L is irradiated with an incident angle θ on the boundary portion of the spark wear resistant electrode material 18 and the outer electrode 16, thereby, the spark wear resistant electrode material 18 is welded to the outer electrode 16. In this case, when the distance from an intersection 11d of the installation face 16b and the end face 11b of a main fitting 11 to an intersection 11e at the furthest end of the end face 11b is made X, and the distance from the intersection 11d to an intersection 18a (closest point) of the spark wear resistant electrode material 18 is made Y, the incident angle θ which satisfies the condition of (X/Y)COPYRIGHT: (C)2007,JPO&INPIT