To provide an oil filter wherein the number of parts for positioning a filter element in a casing can be reduced.

A full-flow filter element 4 comprises a core 401, made of a resin and a filter body 402 formed from acrylic fibers or pulp. The core 401 has an axis part 4014 and a plurality of ribs 4011 formed radially from the part 4014. The part 4014 is formed so as to protrude a vertical protrusion 4012. A horizontal protrusion 4013 is radially projected from a frame. The vertical protrusion 4012 and the horizontal protrusion 4013 are projected from the filter body 402. The part 4012 and the part 4013 are brought into contact with a casing 2 to limit the movement of the element 4.