To prevent a patient from feeling scared by lowering the operation speed of a treatment chair in the case that the patient is an aged person, a pregnant or parturient woman, an injured person or a child, etc.

Operation buttons (switches) 1 and 2 are added by this invention, the operation switch 1 is for a doctor and the operation switch 2 is for an assistant. By pressing the operation switches, the operation speed of the treatment chair 11 is set to be lower than usual and the driving speed of a motor which drives the treatment chair 11 is lowered, for instance. In the case that the patient is the aged person or the child or when it is considered that it is better to lower the moving speed of the treatment chair such as the case of the pregnant or parturient woman, the doctor or the assistant presses the operation switch 1 or 2. Then, the treatment chair 11 is operated at a preset speed lower than normal speed.