A cylinder device includes a recess provided on either one of the piston and the cylinder, the recess facing the other one of the piston and the cylinder; an extension-side discharge passage configured to permit only a flow of liquid from the extension-side chamber toward the recess; a compression-side discharge passage configured to permit only a flow of liquid from the compression-side chamber toward the recess; a tank-side discharge passage configured to allow the extension-side discharge passage and the compression-side discharge passage to communicate with the tank through the recess; an extension-side damping force generation passage configured to apply a resistance to a flow of liquid passing therethrough so as to exert a damping force during extension; and a compression-side damping force generation passage configured to apply a resistance to a flow of liquid passing therethrough so as to exert a damping force during contraction.