To provide an oil filter that is formed of a resin composition and is excellent in at least resistance to engine oil, wherein the resin composition consists solely of a polyamide resin as a resin composition.

The oil filter 1 includes a filter element 2 and a case body 3 for housing the filter element 2. The case body 3 is formed of the resin composition that consists solely of the polyamide resin as the resin composition and that contains an inorganic filler. The resin composition is used which has a tensile strength-keeping rate of ≥80%, as measured after the immersion for 2,000 hours in an engine oil of 130°C, wherein 1 wt.% of moisture is added to the engine oil.