To provide a filter cartridge suitable for changing a horizontal filter device to a cartridge filter and a filter cartridge capable of enhancing the performance of a precoat cartridge filter on the basis of capacity of a filter container.

In comparison with a conventional precoat filter cartridge, the precoat cartridge filter has a greatly enhanced capacity if the outer diameter d of the precoat filter cartridge 1 is decreased. The cross-sectional area of an internal space 6 defined by the cartridge 1 is reduced as compared with the cross-sectional area of an unfiltered liquid space 22. As a result, a mixture of phases during phase change is reduced as well.