The optical tomography imaging system includes a light source, a branching section which branches a light beam into a measuring light beam and a reference beam, an optical probe having an optical fiber, a measurement section which irradiates a measurement target with the measuring beam and picks up a reflected beam, and a sheath which encloses the optical fiber and the measurement section, a multiplexing section which combines the reflected beam with the reference beam to create an interference beam, an interference beam detecting section which detects the interference beam as interference signals, and a contact detecting section which detects a contact area in which the optical probe and the measurement target are in contact with each other. The contact detecting section calculates from the detected interference signals a distance between the optical probe and the measurement target, and uses the calculated distance to detect the contact area.