PURPOSE: To reduce the cause of various trouble due to the maintenance of a filter apparatus by preventing the foreign matter mixed at the replacement time of a filter element from entering a hydraulic lubricating apparatus.

CONSTITUTION: A filter apparatus is constituted of a filter part 1 and a bypass valve 2. The filter part 1 is constituted of a housing 21, a filter element 22, an oil supply inflow port 23 and an oil outflow port 24. The bypass valve 2 is constituted of a valve main body 31, the cylindrical valve element 32 provided in the main body 31 in a freely revolvable manner, an inlet 35 of oil to be treated, an outlet 36 of oil to be treated, a treated oil inlet 37 and a return outlet 39. The inlet 37 and outlet 38 of oil to be treated are allowed to directly communicate each other and the treated oil inlet 37 and the treated oil outlet 38 are allowed to communicate each other through the first through-hole 33 provided to the element 32, while the treated oil inlet 37 and the return outlet 39 are allowed to communicate each other through a through-hole 34, and the axial direction of a hole 34 is turned in the direction crossing the axial line of a hole 33.