[Objective] To realize performance superior in both ignitability and wear resistance.

[Means for Solution] A spark plug 1 includes a center electrode side tip 31 and ground electrode side tip 32, wherein a spark discharge gap 33 is formed between the ground electrode side tip 32 and center electrode side tip 31. An area SA1 (mm²) of a region, on a projection plane onto which the ground electrode side tip 32 and the leading end face of the center electrode side tip 31 are projected on a virtual plane perpendicular to an axis CL1, bounded by a first tangent line TL1, a second tangent line TL2, a projection line of another end face of the ground electrode side tip 32, and a projection line of the outer periphery of the leading end face of the center electrode side tip 31, an area SA2 (mm²) of a region in which projection regions of the two tip 31 and 32 overlap when the center electrode side tip 31 and the other end face of the ground electrode side tip 32 are projected onto a virtual plane parallel to the other end face of the ground electrode side tip 32, and a size G (mm) of the spark discharge gap 33, satisfy 0.12≤SA1×SA2/G(mm²)≤0.49.