To provide a porous filter capable of easily isolating a fluid before treatment and the fluid after treatment when the filter is mounted in a housing, a water cleaner equipped with the filter, a manufacturing method suitable for manufacturing the filter, a press fitting method and apparatus for a sealant suitable for the production of the filter, a sealing method for end surfaces and a sealant applying apparatus.

The porous filter 1 has at least two end surfaces 41 and 43 and a large number of flow channels 3a and 3b communicating from one end surface 41 to the other end surface 43. The predetermined flow channels 3a are sealed in at least one end surface and the height difference between a surface formed by sealing the flow channels and the peripheral surface thereof is not more than 1.0 mm. The water cleaner is equipped with this porous filter. A filter manufacturing method including a press fitting process for pressing a sealant into the predetermined flow channels and a seal process for forming a seal layer to one end surface, the press fitting method suitable for this manufacturing method, the press fitting apparatus, the sealing method and the sealant applying apparatus are also disclosed.