A spark plug includes: a center electrode; an insulating member; a metal shell; a ground electrode; and a cap covers an opening of the metal shell on the front end side to define an auxiliary combustion space in which the gap is disposed, a first angle being formed by a second line and a first tangent line, a second angle being formed by the second line and a second tangent line, the second angle being greater than the first angle, and at least a portion of the opening of the specific through hole on the auxiliary combustion space side being positioned on a range of the second angle.