To provide a filter apparatus which continuously filters floated matter, foreign matter or the like from various waters different in use and various liquids other than water, and a continuous filtering method using this filter apparatus.

The filter apparatus is constituted so that a plurality of cylindrical filters 22 and 23 are arranged in a mutually independently rotatable manner in a cylindrical filter tank 13, of which the cross section cut at a right angle in the length direction of the filter tank is circular, rectangular, polygonal or oval, as a set along the length direction of the filter tank so that the outside surfaces of the filters are adjacent to each other to leave a mutually narrow interval. A washing liquid jet means for washing one surface of each cylindrical filter is installed in a V-groove formed by the constricted part of the narrow interval between the outside surfaces of a set of two mutually adjacent cylindrical filters while a drain chamber is installed in the other V-groove and a liquid 11 to be filtered is continuously filtered by the filter apparatus.