To provide a height adjustment leg capable of obtaining a larger elevating/ lowering stroke with a small manipulated variable at the time of using the screw of a general standard.

This height adjustment leg is provided with a fixed member 5 provided with a first female screw 4 and fixed to a base 3, a rotation member 9 provided with a first male screw 6 to be screwed to the first female screw and a second female screw 8 in the opposite direction of the first female screw coaxial to the first male screw, a stroke member 12 provided with a second male screw 10 to be screwed to the second female screw whose end part is grounded and a rotation stop means 13 for controlling relative rotation between the fixed member and the stroke member. Thus, when the rotation member is twisted and the first male screw is screwed to the first female screw of the fixed member, the stroke member which is the opposite screw of the first female screw and is rotation stopped to the fixed member is moved in the same direction as the axial direction movement of the rotation member accompanying the screwing of the first male screw to the first female screw. Thus, an extension/contraction stroke between the fixed member and the grounded end of the stroke member to the twist amount of the rotation member is doubled.