PURPOSE: To form a filter having first and second filter elements and a heat exchanger into an integral body by forming in a heat exchange a sub-flowpath which communicates with the second filter element of the filter.

CONSTITUTION: In a heat exchanger B are formed an oil communication passage C, a main oil flow-in path D for introducing a lubricating oil which has been filtrated and become pure by a first filter element 1 to carry out heat exchange in the heat exchanger B, and sub oil flow-in path E which introduces the lubricating oil which has been filtrated by the second filter element 4 of the filter A. The lubricating oil containing carbon minute particles in the lubricating part of an internal combustion engine reaches an oil flowpath of the filter A from an oil flow-in path 57a of a mounting member 57 via the oil communication path C. A part of oil passes through a communicating hole 3b of the member 3 and flows into the first filter element 1, and another part of oil passes through a filter paper 21 on the upstream end and flows into the second filter element 4. Thereafore, a pipe which prevents the integral loading of the heat exchanger and the filter, can be removed and the heat exchanger and the filter can be formed into an integral body.