Abstract: [Problem to be Solved] To reliably make oil flow into a drain passage at the time of replacing a filter element or the like. [Solution] An oil filter 1 includes a housing 5 and a cap member 6 that form a space for containing a filter element 7. An engaging portion 23 is provided to the cap member to engage the filter element. Also, a communication portion 11 connected to the inner circumferential space of the filter element, a drain channel portion 12 provided annularly to encircle the communication portion, and an inflow side channel portion 13 provided annularly to encircle the drain channel are provided at the bottom portion of the housing. A gasket 35 abutting a partition wall 14 and suppressing a flow of yet to be filtered oil into the drain channel is provided at the bottom portion of the filter element.