A vehicular air conditioning device includes a damper and a unit case in which a shaft receiving hole is formed for supporting the damper. The damper includes a rotating shaft portion extending in an axial direction, and a plate-like first damper body extending from the rotating shaft portion. The rotating shaft portion includes a flange portion provided at only a partial region in the circumferential direction of the axis. The inner wall surface of the unit case includes an elongated protrusion, with which a first damper plate surface of the first damper body is contactable from another side in the circumferential direction, and a contact portion with which a second damper plate surface of the first damper body is contactable from one side in the circumferential direction. A radial space between a radially inward end part of the elongated protrusion and a shaft receiving hole is less than a radial size of the flange portion.