A metal gasket includes: a straight section provided with a bolt hole; a bead section raised from an inner peripheral edge of the straight section toward one side of the direction of the thickness of the gasket; and a bent section bent from an outer peripheral edge of the straight section toward the other side of the direction of the thickness of the gasket. When metal gasket is compressively sandwiched by a pair of housings, bead section elastically deforms to decrease height, and straight section elastically deforms, whereby the inner peripheral edge of the straight section contacts one of the housings, the outer peripheral edge of the straight section contacts the other housing, and the bent section contacts the one of the housings. A gasket installation determination projection is part of the periphery and provided on the outer peripheral edge of the bent section or of the straight section.