Included are: a shade; a housing member to which the shade is mounted so as to be extended/housed through an opening; a lid body disposed in the housing member so as to open/close the opening and configured to rotate about a rotation axis of a shaft portion between an opened position and a closed position along with an extending/housing movement of the shade; and a spring member configured to bias the lid body in a rotation direction. The spring member is disposed so as to change a direction of a biasing force along with a rotary movement of the lid body so that a rotational biasing force in an opening direction is exerted on the lid body in a state in which the lid body is opened and that a rotational biasing force in a closing direction is exerted on the lid body in a state in which the lid body is closed.