To perform both of minute adjustment and large adjustment of a projection amount of a leg body from an adjusting object by operating an operation part at one location.

A height adjusting mechanism is equipped with a mounting base 1 for the adjusting object P, the leg body 2 assembled slidably in the vertical direction to the mounting base 1, a rotation operating body 3 having a larger inner diameter than an outer diameter of the leg body 2 and having a female screw part 30 on the inner peripheral part, with its outer peripheral part rotatably assembled to the mounting base 1 as the operation part 31, and a biasing body 4 of the rotation operating part 3. The leg body 2 has a male screw part 20a inserted inside the rotation operating body 3 and engageable with the female screw part 30 of the rotation operating body 3. The female screw part 30 and the male screw part 20a are engaged by biasing of the biasing body 4 so that the leg body 2 is threadedly advanced and retreated in the vertical direction by rotational operation of the rotation operating body 3.