Spark plug and method for manufacturing spark plug

A method for manufacturing a spark plug, the method comprising the steps of:

• placing a cap at a specific position which covers an opening of a metallic shell located at a front side of the spark plug, said metallic shell having a through hole extending in a direction of an axis;
• and
• welding the cap placed at the specific position to the metallic shell,
• wherein the metallic shell and the cap placed at the specific position form an annular gap which communicates with a specific space surrounded by the metallic shell and the cap and is interposed between the metallic shell and the cap,
• the annular gap includes:
• a first gap which communicates with the specific space;
• and
• a second gap which communicates with the specific space and is larger than the first gap, and
• the step of welding the cap to the metallic shell further comprises the sub-steps of:
• welding a specific portion whose position in a circumferential direction is different from that of a specific second gap, of a boundary between the cap and the metallic shell which communicates with the annular gap;
• and
• after welding the specific portion, welding a portion whose position in the circumferential direction is the same as that of the specific second gap, of the boundary.