<；P>；PROBLEM TO BE SOLVED: To provide an external filtering device which includes a simple and compact electric suction pump for priming having a sufficient pump performance. <；P>；SOLUTION: This external filtering device 1 is arranged independently from a water tank, pumps up water in the water tank, allows the water to pass through a filtration tank 12, and returns the water again into the water tank. The external filtering device 1 includes: a flow passage 17 for water pumped up from the water tank； a circulation pump 13 sucking and delivering the water supplied to the filtration tank 12； a check valve 19 provided in the flow passage 17, allowing a flow of water from an upstream side 17a to a downstream side 17b, and preventing the flow of water from the downstream side 17b to the upstream side 17a； and the electric suction pump 100 sucking and delivering air and water, having a suction port 141 connected to the upstream side 17a of the flow passage 17 and a delivery port 142 connected to the downstream side 17b of the flow passage 17, and priming the circulation pump 13. <；P>；COPYRIGHT: (C)2011,JPO&INPIT
