This disclosure provides a radome to be installed on an emission face side of an antenna, which includes an outer wall having a side cross-section formed in a substantially semi-circular shape to include the antenna therein, and an inner wall arranged between the outer wall and the antenna, and formed in a shape to substantially conform to the outer wall. A gap between the outer wall and the inner wall is wider near both ends on the circumference of the substantially semi-circular shape than at a substantially midpoint on the circumference of the substantially semi-circular shape.