To provide an oil/water separation filter which surely and quickly separates oil from mixed water, is continuously usable without clogging, easily disposing removed oil, is easily used, is usable as it is for a filter used in various kinds of conventional waste water treating means, and is usable in a simple device in a sink of a restaurant or a household or the like as well.

The oil/water separation filter comprises a hydrophilic porous body which has the continuous pores of a pore diameter being 10-700 μm and whose water retention percentage is 100-1,400%. When moisture is contained in the oil/water separation filter 1 before starting separation work, all the continuous pores of 10-700 μm are filled with the water, also, since the water retention percentage is as high as 100-1,400%, the entire filter contains the water and becomes a wet state. When the mixed water is poured to the filter in the state, the moisture passes through the filter by the gravity through the continuous pores and an original state is restored.