Provided is a technique which realizes securement of gas-tightness and suppression of loosening of a gasket. A spark plug includes a tubular metallic shell extending in an axial direction, and an annular gasket provided around the metallic shell. The gasket is solid and contains copper as a main component and nickel in an amount of 0.1 wt. % or more. The gasket has a maximum thickness of 0.4 mm or more in the axial direction, and the gasket has a Vickers hardness of 30 HV to 150 HV.