A Jones matrix OCT is realized, which offers improved image stability, image quality, and depth range of image. The light from a wavelength-scanning light source 6 is split into two optical paths, and a reference arm 12 is provided along one optical path, while a probe arm 13 that irradiates and reflects light onto the measuring target to generate object light is provided along the other optical path, wherein the probe arm 13 has a polarization delay unit 21 that linearly polarizes the light and then splits it into S-wave component and P-wave component, where the S-wave component and P-wave component are superimposed through optical paths of different optical path lengths, respectively, after which optical detectors 68, 70 are used to detect different spectral interference beams in the depth direction of the measuring target corresponding to the vertically polarized component and horizontally polarized component, which respectively correspond to the S-wave component and P-wave component, to obtain four spectral interference signals.
