To provide technology for suppressing that a tool engagement part of a main metal fitting swells outside when a spark plug is manufactured.

A method for manufacturing a spark plug includes the steps : (a) preparing a member at a state that an insulator is inserted into a main metal fitting; and (b) fixing the main metal fitting and the insulator by a jig. The step (b) includes a step of arranging a position of the tip of a taper surface of the jig in the center line direction at the same position as the rear end of a tool engagement part, or at a position closer to the tip side than the rear end of the tool engagement part, and bringing the taper surface of the jig into contact with at least a part of an inclined surface located on the rear end side from the tool engagement side and the tip side from a swage part. When an angle of an acute angle to be formed between the center line and an extended line of the taper surface of the jig is considered as A, and an angle of an acute angle to be formed between the center line and an extended line of the inclined surface of the main metal fitting is considered as B, relation of -3°≤B-A≤10°is satisfied.