A casing for a laser spark plug, in particular, of an internal combustion engine of a motor vehicle, or of a stationary engine; the casing including at least one casing part and a combustion chamber window joined to the casing part to form a seal at least regionally; characterized in that at least one sealing element, whose coefficient of thermal expansion at an operating temperature of the laser spark plug is greater than the coefficient of thermal expansion of the casing part at the operating temperature of the laser spark plug, is provided between the casing part and the combustion chamber window.