A movable support structure, wherein the retaining/restricting portion is resiliently deformable in a direction to be retracted from a relative passage path for the receiving portion when the supported portion is inserted into the movable supporting portion from a catching posture, in which the retaining/restricting portion is caught by the receiving portion, with the supported portion supported by the movable supporting portion, and the deformation restricting portion restricts resilient deformation of the retaining/restricting portion in a direction to be retracted from the catching posture.