To perform mounting and demounting of a plurality of oil filters, different in an outside diameter from each other, by a single wrench for a oil filter.

A rotation driven part 12 is mounted on the outer surface of a rotary disc 11 and two fastening members 21 and 22 are mounted on the inner surface of the rotary disc 11. The fastening members 21 and 22 are provided with arm parts 23a and 23b, rotatably attached to the rotary disc 11 and arcuate parts 24a and 24b, respectively, arranged thereat. A spring force in a direction in which the fastening members are caused to approach each other is energized on the fastening members 21 and 22 through compression coil springs mounted on the arm parts 23a and 23b. Through rotational drive of the rotary disc 11 with the arcuate parts 24a and 24b brought into contact with a filter case 35, the filter case 35 is rotated.