To ensure that the air does not remain in a main body of a pump or in discharge piping.

In the fire fighting pump wherein a vacuum pump is connected through suction piping to a proximal end part of intake piping fixed to an intake aperture of the main body of the pump and the air in the intake piping is absorbed through the suction piping by the above vacuum pump to pump up the water into the main body of the pump through the above intake piping, discharge piping is connected through a back flow valve to the discharge aperture of the main body of the pump and a ventilation valve is connected through an exhaust pipe to the above discharging piping. Thereby the air remaining in the main body of the pump or in the discharge piping can be discharged through the exhaust pipe by the ventilation valve.