Abstract: An oil filter assembly comprises: a cylindrical main housing having an open upper end; a cover assembled with an upper end thereof; an impeller housing disposed beneath a lower surface thereof; a mixer disc fixedly inserted in the impeller housing; an impeller disposed on an upper surface of the mixer disc to mix foreign material contained in an oil; an adjust housing disposed under the impeller to supply the oil when an engine is operated; a filter member for filtering off the foreign material from the oil supplied from the impeller; an overflow valve for controlling a quantity of introduced oil and capturing metallic foreign material from the oil supplied from the impeller by means of a magnetic force; and a fixing-and-oil-discharging bolt for assembling elements disposed in the main housing by means of the cover and supplying the oil filtered and cleaned to parts of an engine.