Disclose herein is an exhaust valve capable of quickly discharging either a fluid in a cylinder or compressed air in a pneumatic tank therefrom. The exhaust valve is basically provided with a first port, a second port, a third port and a directional control valve. The first port is supplied with a fluid and the second port is used to supply the fluid to another device or receive it therefrom. The third port is used to discharge the fluid therefrom and comprises a rotatable L-shaped line or pipe. The directional control valve is switched to cause the first port to communicate with the second port or cause the second port to communicate with the third port in response to the pressure of the fluid supplied from each of the ports. The first and second ports have axial directions respectively which substantially coincide with each other or extend approximately in parallel. Therefore, the first and second ports can be incorporated in the course of a pipe without making a change in a piping direction. Since the third port comprises the rotatable L-shaped line, the axial direction of the third port can be suitably changed to a desired direction.