Abstract: According to the vertical pump of the present invention, a reverse U-shape air suction passage is connected to a suction casing which communicates with the impeller chamber, and a U-shape branch passage is branched from a hanging portion of the air suction passage. According to this vertical pump, when the water level is raised in the air operation state, air suction into the suction casing through the air suction passage and the branch passage is stopped when the water level reaches the pumping starting water level, so that the operation of the vertical pump may be changed to the water pumping operation. Where the water level is lowered in the state of water pumping operation, air suction into the suction casing through the branch passage and the air suction passage may start at the pumping stopping water level which is lower than the pumping starting water level. Accordingly, the operation of the vertical pump may be changed to the air operation.