To make a level adjuster not require large operation force for adjusting height, by equipping a screw shaft with a hemisphere part and a foot part with large slide friction on the lower end and rotating the screw shaft until the level adjuster main body comes to prescribed height and the foot part is grounded and the foot part is floated up from the floor.

This level adjuster has a hemisphere part 11a on the lower end of a screw shaft 11 screwed to the main body and fixed by a nut 9. The adjuster also has a grounding part 15 made of rubber with large slip friction with a through hole 15a on the center, which is formed into a circle with the diameter larger than that of the screw shaft 11 and is to be inserted with the screw shaft 11. The grounding part 15 is mounted inside the grounding part cover 14 by adhesion, etc. When an operation table is fixed, the screw shaft 11 is rotated to be protruded downward to ground the hemisphere part 11a onto the surface of a floor 10. By rotating the screw shaft further, a carrier is floated up from the floor 10. The screw shaft 11 is rotated further until the height of the main body reaches the prescribed height and fastened to the main body by a nut.