To provide a seawater intake/supply pump apparatus low in cost, high in reliability and having corrosion resistance to seawater without using a special high-cost pump and equipment.

This seawater intake/supply pump apparatus is provided with a suction header pipe 18 to which a seawater intake pipe 101 is connected; seawater supply pumps 11, 11 with the suction ports connected to the suction header pipe 18; discharge pipes 19, 19 connected to discharge ports 11b, 11b of the seawater supply pumps 11, 11; and a vacuum generator (a vacuum pump 14 or the like). In starting, the vacuum generator is started to suck air in the suction header pipe 18 and to fill the inside of the suction header pipe 18 with seawater, and the seawater supply pump 11 is started to supply the seawater to a prescribed place through the discharge pipe 19. A liquid contact part in contact with the seawater is provided with resin lining, and/or the liquid contact part is formed of a resin material.