To provide an easy-to-use and inexpensive dental treatment chair in a simple configuration.

A lifting device of dental treatment chairs comprises: a treatment table 2, a support member 3 vertically moving while supporting the treatment table in a cantilevered state; a screw shaft for vertically moving the support member; a main guide shaft 5 and a sub guide shaft 6 for guiding the vertical movement of the support member; a base 7 and a roof 8 that fix the upper ends and the lower ends of the screw shaft, the main guide shaft, and the sub guide shaft; and a plurality of supports 9 that are erected surrounding the screw shaft, the main guide shaft 5 and the sub guide shaft, and the upper/lower ends of which are fixed to the base and the roof.