It is well known that the massage therapy is useful for the rehabilitation of various diseases (i.e. oral health problems, ete.), Although various apparatus have been developed for the massage of the torso and limbs, there is still little knowledge about their real effectiveness. For this purpose, authors have proposed the development of a robotic system that provides massage therapy of the maxillofacial region to patients with temporomandibular joint disorders. As a result of our research, we have developed the Waseda-Asahi Oral-Rehabilitation No.1 (WAO-1), which it is composed by two six-degrees of freedom arms with plungers attached at their end-effector. Preclinical tests were carried out to confirm the effectiveness of the proposed system. In order to evaluate the safety measures of the applied forces during the massage therapy, we have based our analysis on the Visual Analogue Scale (VAS) which is a conventional subjective evaluation methods commonly used in the medical field. From the experimental results, we could confirm the effectiveness of the therapy provided by WAO-1.