PURPOSE: To make loosening and fastening of a cylinder head member easily to a certain degree and safely by furnishing a location adjusting mechanism, which adjust a cylinder fixing table in the direction of approaching and separating to/from a receptacle table, between the cylinder fixing table and the body of a working table.

CONSTITUTION: The distance between a cylinder fixing table 3 and a receptacle table 4 is adjusted to a value in accordance with the length of cylinder by adjusting the cylinder fixing table 3 with a location adjusting mechanism A. Even when the cylinder length differs, the cylinder fixing table 3 is allowed to act on one end of a cylinder tube 11 and the receptacle table 4 on the other end by putting the cylinder fixing table 3 into the operative condition. This cylinder tube 11 is firmly fixed to the body 2 of a working table so that the cylinder tube 11 does not rotate or dislocate when a cylinder head member 20 is rotated, and thus it is made harder for a wrench fitted on the cylinder head member 20 to be put off. Thus loosening and fastening of the cylinder head member 20 is performed while transmission of the operating force is made certainly.