A spark plug includes a tubular housing, a tubular insulator, a center electrode, a ground electrode, a resistor, and a stem. The insulator is supported inside the housing. The center electrode is supported inside the insulator so as a distal end portion thereof protrudes. The ground electrode forms a spark discharge gap G between the ground electrode and the center electrode. The resistor is supported inside the insulator at a proximal side of the central electrode. The stem is supported inside of the insulator at a proximal side of the resistor. Of an outer peripheral surface of the insulator, and closer to a distal end side than a proximal portion of the resistor is, there is formed a high emissivity surface of which thermal emissivity is at least 0.7 on at least a part of a portion facing an inner circumferential surface of the housing.