Eye contact plays an important role as a regulator in human face-to-face communication, and has been confirmed to have a close relationship with mental health. Therefore, it is essential to establish a quantitative evaluation for estimating the degree of mental health through eye contact. In this paper, we propose a method for measuring the level of eye contact and describe the development of an eye contact measurement system that utilizes a virtual display in face-to-face communication. As the virtual display in this system, a dichroic mirror that can transmit visible rays and reflect infrared rays is arranged between two talkers. This system enables the gaze points and the recognizable area of eye contact to be detected for both talkers using image processing, and helps evaluate whether eye contact has been established. In addition, the effectiveness of the developed system is demonstrated experimentally.