INTERNAL COMBUSTION ENGINE

An engine includes a cylinder, a ceiling section, a guide wall, a recess. The guide wall is provided in the ceiling section of a combustion chamber and is connected to openings of the intake/exhaust port. The recess provided in a portion of the guide wall and is recessed in a direction to separate from a center axis of the cylinder. The internal surface of the recess is inclined such that a lower end of the recess is farther away from the center axis of the cylinder than an upper end of the recess. The recess is recessed the most at a second position where the recess crosses a tangent of the first opening. The tangent contacts a first portion of the first opening. The first portion is the closest portion of the first opening to the exhaust port.