<；P>；PROBLEM TO BE SOLVED: To provide an internal type filter device； which is equipped at any place for a water tank and is composed as a unit body； which increases the filtration efficiency of the filter medium and reduces clogging； and which makes it easy to assemble in the filter case. <；P>；SOLUTION: The filtering unit U is composed as a unit body of the rotary shaft 10, which is pivotally axially supported with free rotation in the filter case 1, and the water wheel 11 and filter medium 12 which can rotate integrally with the rotary shaft 10. The filtering unit U is assembled in the filtering case 1 and is rotated by the tank water introduced into the filter case 1 by the pressurized air from the air pump P. <；P>；COPYRIGHT: (C)2011,JPO&INPIT
