An illumination apparatus includes a light-emitting element, a first lens, and a second lens. A first incident surface of the first lens faces the light-emitting element, and guides a light beam from the light-emitting element to a radiation port. A second incident surface of the first lens guides a light beam not passing through the first incident surface to a direction toward the outer periphery of the first lens. A first reflection surface of the first lens reflects a light beam from the second incident surface to guide the light beam to the radiation port.