A lamp achieves high output power like an HID lamp by using a light emitting element(s) as a light source. A mount board having LED mounted thereon is provided on the surface of a base member, and there are provided plural flat plate type light source units arranged around an axial line while the back surfaces thereof faces inwards, and a support member provided on the axial line. The plural light source units are supported on the support member, and a space through which air flows is provided at the back surface side of each base member.