Engine head structure

An injector, a spark plug and a pressure sensor are assembled integrally in a common housing. The common housing is fixed in a mounting hole provided in a cylinder head of an engine so that tip end portions of the injector, the spark plug and the pressure sensor face inside of the cylinder room. For example, a gasket having heat resistance can be provided between a lower end portion of an outer wall of the common housing and an inner wall of the mounting hole for the air-tight sealing. Furthermore, a concave portion may be provided at an outer portion of the common housing so as to form a coolant passage.