To quickly supply water while preventing damage of an engine caused by overheat/seizure of the engine driving an impeller.
In a portable fire engine, an intake flow passage communicates with an inlet port of an impeller chamber, and a discharge flow passage communicates with a discharge port of the impeller chamber. By rotations of the impeller in the impeller chamber, the water is sucked up through the intake flow passage and is discharged through the discharge flow passage. A sensor chamber is continuously disposed to communicate with an upper position of the intake flow passage through a communicating passage, a high water level sensor is disposed in the sensor chamber, and a priming pump is continuously disposed to communicate with the sensor chamber, so as to rotate the impeller. The priming pump is driven to make the intake flow passage and the sensor chamber be an approximately vacuum, so as to supply the water to the impeller chamber and the sensor chamber. When the high water level sensor detects that water level in the sensor chamber supplied with water reaches a predetermined water level, the priming pump is stopped.