To attempt reducing machining cost of an oil filter mounting part or the like in a chain case in which the oil filter is installed.

An oil filter mounting part 12 which protrudes from the case body 11 to the outside along the parallel direction to a joining surface 10 (a joining surface with an engine block 100a) of the chain case 1 is arranged in a case body 11 covering a timing chain. Then, an oil filter mounting surface 13 is formed in an engine block side of the oil filter mounting part 12 and the oil filter mounting surface 13 is parallel to the joining surface 10. In the structure, one part of an oil passage of the oil filter mounting part 12 can be formed without using a slide die and machining shafts, such as bolt hole machining can be made common, thereby machining cost can be reduced.