A spark plug includes an insulator situated in a housing, in which the insulator has a sealing surface which lies against a sealing surface of the housing or against a sealing element that is situated between the housing and the sealing surface of the insulator. An arrangement exerts a force on the insulator that is directed in the longitudinal direction of the spark plug in such a way that the sealing surface of the insulator presses upon the sealing surface of the housing or upon the sealing element, and thus the insulator in the housing is sealed in a gastight manner.