A corner reflector configured to reflect a radio wave, the corner reflector comprising: three annular balloons (3a, 3b, 3c) each of which has flexibility and airtightness, and, configured to expand in an annular shape extending in an annular direction around a virtual central axis due to gas pressure, when gas is supplied to an inside of the balloons, and radio wave reflective films each of which includes an outer peripheral edge portion attached to the annular balloon wherein the radio wave reflective films are configured to be developed to a plane due to the expansion of the annular balloon, wherein the three annular balloons are configured such that they can be brought into an expansion state to such an extent that the three annular balloons are made orthogonal to each other, the corner reflector further comprises a constraint fabric wound around each of the annular balloons in a winding direction orthogonal to the annular direction, the constraint fabric is configured to support surface pressure from the annular balloon in the expansion state where the annular balloon annularly expand, to thereby restrict expansion of the annular balloon, and wherein the constraint fabric includes an inner peripheral side fabric portion and an outer peripheral side fabric portion configured to extend in the annular direction in the expansion state, wherein the outer peripheral side fabric portion is located further from the virtual central axis of the annular balloon in the expansion state, than the inner peripheral side fabric portion and characterized in that, the elongation degree of the outer peripheral side fabric portion in the annular direction is higher than the elongation degree of the inner peripheral side fabric portion in the annular direction, wherein the elongation degree is defined as a numerical value representing an elongated amount of a fixed unit length of the constraint fabric when the constraint fabric is elongated due to a fixed tensile force acting on the constraint fabric from a state where no external force acts on the constraint fabric. three annular balloons (3a, 3b, 3c) each of which has flexibility and airtightness, and, configured to expand in an annular shape extending in an annular direction around a virtual central axis due to gas pressure, when gas is supplied to an inside of the balloons, and radio wave reflective films each of which includes an outer peripheral edge portion attached to the annular balloon wherein the radio wave reflective films are configured to be developed to a plane due to the expansion of the annular balloon, wherein the three annular balloons are configured such that they can be brought into an expansion state to such an extent that the three annular balloons are made orthogonal to each other, the corner reflector further comprises a constraint fabric wound around each of the annular balloons in a winding direction orthogonal to the annular direction, the constraint fabric is configured to support surface pressure from the annular balloon in the expansion state where the annular balloon annularly expand, to thereby restrict expansion of the annular balloon, and wherein the constraint fabric includes an inner peripheral side fabric portion and an outer peripheral side fabric portion configured to extend in the annular direction in the expansion state, wherein the outer peripheral side fabric portion is located further from the virtual central axis of the annular balloon in the expansion state, than the inner peripheral side fabric portion and characterized in that, the elongation degree of the outer peripheral side fabric portion in the annular direction is higher than the elongation degree of the inner peripheral side fabric portion in the annular direction, wherein the elongation degree is defined as a numerical value representing an elongated amount of a fixed unit length of the constraint fabric when the constraint fabric is elongated due to a fixed tensile force acting on the constraint fabric from a state where no external force acts on the constraint fabric.