A valve stem seal hermetically seals a space formed between a valve stem of a valve which establishes and interrupts communication between a cylinder and a port and a valve guide into which the valve stem is inserted in a reciprocally movable manner, wherein the valve stem seal includes: a reinforcing ring formed into an annular shape centered about an axis, and extending in a radial direction of a ring of the reinforcing ring; and an elastic body portion formed into an annular shape centered about the axis, attached to the reinforcing ring, and including a seal lip which abuts on the valve stem.