DOOR BEAM

A door beam includes: an upper inner flange; a lower inner flange; an outer flange; an upper rib; and a lower rib. A thickness of the outer flange is larger than a thickness of the upper inner flange and a thickness of the lower inner flange. A thickness of the upper rib becomes gradually larger from the outer flange toward the upper inner flange, and a thickness of the lower rib becomes gradually larger from the outer flange toward the lower inner flange.