A corner reflector includes: annular hollow balloons having flexibility and airtightness, and when gas is supplied therein, the annular hollow balloons expand with pressure of the gas to be an annular shape; and a radio wave reflection film having an outer edge part that is attached to the annular hollow balloons so that expansion of the annular hollow balloons makes the radio wave reflection film unfold over a plane of the annular shape. The three of the annular hollow balloons are provided so as to be mutually orthogonal after expansion. Binding members are attached to outer faces of the annular hollow balloons, the binding members being for preventing expansion of the annular hollow balloons beyond their limit volume.