1. An optical coherence tomography method that divides light from a light source into measurement light and reference light and acquires a tomographic image of an object to be measured based on a wavelength spectrum of coherent light of the reference light and return light, the return light returning from the object to be measured upon irradiating the measurement light onto the object to be measured, the optical coherence tomography method comprising the steps of: dividing the object to be measured into a plurality of measurement regions adjacent to one another in a direction of irradiation of the measurement light, and acquiring a measurement image for every measurement region based on the wavelength spectrum of the coherent light; and acquiring a tomographic image for every measurement region by removing a mirror image of the tomographic image of an adjacent region being adjacent to the measurement region of the measurement image from the measurement image.