To provide a damper device. Rotary vanes 18 installed protruding from a rotary shaft 12 partition the space between the cylindrical inside wall 22a of a casing 22 and each bulkhead 23 extending in the radial direction into a pressurized oil chamber 24a and a decompression oil chamber 24b, and a notch for an oil passage 28 is formed in the central part in the axial direction. A check valve 20 to seal the oil passage 28 is furnished consolidatedly with an elastic projection 30-1 located internally opposite the pressure receiving surface 20a, and at normal time, a V-form leg opening part 31-1 puts the check valve 20 in pressure attachment to the rotary vanes 18, and with rotation in the CW direction, the oil passage 28 is opened by the oil pressure to generate rotation in a light motion, and with a rotation in the CCW direction, the sealed condition is restored immediately and a braking motion is actuated. |