There has been conventionally known a brake cylinder device in which a parking spring brake mechanism can operate, as a brake cylinder device used in a brake device for a railway vehicle. For example, Patent Literature 1 discloses a unit brake (a brake cylinder device) provided with a wedge (a brake force transmitting section) that transmits a moving force of a piston to a push-rod (brake output section) via an inclined surface. In this arrangement, a pressurized fluid is discharged from a pressure chamber, and the brake output section is pressed by the brake force transmitting section due to a biasing force of a spring, such that a spring brake means (a parking spring brake mechanism) outputs a brake force.