Structure information with a middle layer in a measured object having a layer structure as a basal plate is visually determined. A processing section (22) is configured by including an optical structure information detecting section (220), an optical stereoscopic structure image constructing section (221), a middle layer extracting section (222) as a middle layer extracting device, a flattening processing section (223) as a layer flattening device, an optical stereoscopic structure image converting section (224) as a structure image converting device, a horizontal tomographic image generating section (225) as a region information extracting device and a horizontal sectional image generating device, an image synthesizing section (226) as an image synthesizing device, a display control section (227) as a display control device and an I/F section (228).
