Abstract: A manufacturing method for manufacturing a spark plug including a rod-shaped center electrode extending in an axial direction, an insulator having a tubular shape having an axial hole and holding the center electrode in the axial hole, a metal shell having a tubular shape having an end surface and an inner peripheral surface, a gap being formed between a leading end side of the insulator and the inner peripheral surface, and a ground electrode welded to the end surface, the manufacturing method including welding the ground electrode to the end surface, and removing welding sag, which is formed inside the metal shell by the welding, by causing a tip end portion of a linear member to come into contact with the welding sag while rotating a tool in which a base end portion of the linear member is fixed.

Abstract: A manufacturing method for manufacturing a spark plug including a rod-shaped center electrode extending in an axial direction, an insulator having a tubular shape having an axial hole and holding the center electrode in the axial hole, a metal shell having a tubular shape having an end surface and an inner peripheral surface, a gap being formed between a leading end side of the insulator and the inner peripheral surface, and a ground electrode welded to the end surface, the manufacturing method including welding the ground electrode to the end surface, and removing welding sag, which is formed inside the metal shell by the welding, by causing a tip end portion of a linear member to come into contact with the welding sag while rotating a tool in which a base end portion of the linear member is fixed.