To provide an oil filter device simplified in structure and reduced in size by a valve element mechanism reduced in size while securing the strength of a projected part.

This oil filter device comprises a filter housing formed of a housing body and a cover member, a filtrating body stored in the filter housing, a discharge passage formed in the filter housing, the projected part disappearably mounted at the opening part of the discharge passage and allowed to come into contact with the filtrating body, an energizing member energizing the projected part so as to be projected to the filtrating body side, and a valve mechanism formed of a stopper part formed integrally with the projected part and restricting the projection of the projected part by a specified amount or more by coming into contact with a contact part formed near the opening part of the discharge passage and an open/close mechanism opening/closing the discharge passage according to the movement of the projected part. The contact part is brought into contact with the stopper part at a plurality of positions in the circumferential direction, and ribs extending from clearances at the contact parts to the tip side are formed integrally with the projected part.