PURPOSE: To apply a pressing force onto a pressed member without generating the large defects and strains on a fixed member by installing an expandable part for press-attaching the extension part of an outer cylinder body onto a supporting member on the insertion into an outer cylinder body and a pressing part which is screwed with the spread part and presses the pressed member.

CONSTITUTION: An expandable pipe 23 is inserted into an outer cylinder body 18, and the extension part 20 of the outer cylinder 18 is spread outwardly and press-attached onto a supporting member (interruptor side flange) 3 formed integrally with a pressed member (seat metal) 30. A pressing part (pressing bolt) 29 is screwed with a screw formed in the hollow penetration part of the expandable pipe 23 and allowed to project from the top edges of the outer cylinder body 18 and the expandable pipe 23 on the intrusion into the hollow penetration part, and the pressed member 30 is pressed by the top edge of the pressing part 29. The reaction force which is received by the pressing part 29 from the pressed member 30 is received by the supporting member 3. Therefore, the pressing force can be applied onto the pressed member 30 without generating the large defects and strains on a fixed member.