To simplify the assembling structure of an element S/A (an element assembly for an oil filter) for filtering an oil and improve the assembling reliability and the workability.

In order that filter elements 21 for full flow, which are components of an element S/A 20 of an oil filter 100, is to be made a formed body integrally molded with fibers; the tip end part 25a of a protector member 25 of a filter element 24 for bypass flow is joined to an extended part 22a of the protector member 22 to be formed by resin molding by utilizing impregnation with, for example, a phenol resin being processed in the manufacturing process without using an adhesive. Consequently, the assembling structure of the element S/A 20 is simplified and the cost is reduced and further, since no packing is used, the assembling reliability and workability can be improved.