A massage unit of a massage device moves upward and downward along a backrest of a chair. A pair of therapeutic arms are pivotably supported on a pair of pivot arms projecting forward when viewed from the backrest. Therapeutic fingers on the therapeutic arms have massage balls disposed on them. The pivot arms are driven to move the therapeutic arms in three dimensions, i.e., up and down, left and right, forward and back, so that a patient is massaged by the massage balls. An angle detector detects the angle of the therapeutic arms relative to the pivot arms. The magnitude and change in the output of the detector is used to determine the portion of the patient's body that is being contacted by the massage balls at any time.