A handle is supported by a hollow tube so as to be movable in the direction in which the handle is pushed toward a hollow space. A hole leading to the hollow space of the hollow tube has a first hole portion located at one end of a base portion extending in a longitudinal direction L of the hollow tube and a second hole portion extending from the first hole portion to a portion corresponding to the other end of the base portion in the longitudinal direction L. A dimension W2b of a grip portion of the handle in a width direction W is greater than a dimension W2a of the base portion of the handle in the width direction W and greater than a dimension W1a of the second hole portion in the width direction W.