A variable damping-force damper includes a cylinder tube filled with magnetic particles (MRF), a piston that is slidably disposed within the cylinder tube, a piston rod connected with the piston and is disposed so as to protrude out of one end of the cylinder tube and a rod guide that closes one end of the cylinder tube and slidably supports the piston rod. The cylinder tube has a Ni plating film whose Vickers hardness is 800 VHN or more on its inner peripheral surface and the piston slides relative to the Ni plating film. The rod guide has a structure having a predetermined base material portion and a fluorine resin contained Ni plating film that is treated by heat and is provided on the surface of the base material portion. The piston rod slides relative to the fluorine resin contained Ni plating film.