1. An optical image measuring device comprising: an optical system that splits a low-coherence light beam into signal light and reference light, generates interference light by causing said signal light propagated through a measured object and said reference light propagated through a reference object to interfere, and generates detection signals by detecting said interference light; and an image forming part that forms a tomographic image of said measured object based on said detection signals; said optical image measuring device comprising: an alignment part that performs alignment of said optical system with respect to the measured object; a focusing part that focuses said optical system with respect to the region of interest of said measured object; a determining part that determines the suitability of the position of said optical system by said alignment part, the suitability of the focus state by said focusing part, and the suitability of the position of the tomographic image of said region of interest in a frame that is formed by said image forming part; and a control part that, when it is determined that all of the position of said optical system, the position of said focus state and the position in said frame are appropriate, controls said optical system and said image forming part, making it possible to obtain the tomographic image of said region of interest.