An optical imaging method is provided that can realize, at low cost, the extension of the imaging depth range. An optical imaging apparatus 400 is an apparatus that forms a tomographic image of an object using FD-OCT, and performs a scanning step, detection step and imaging step. In the scanning step, the object is scanned with a signal light while alternately changing the phase difference between the signal light and a reference light to two preset phase differences. In the detection step, interference light of the signal light passing through the object and the reference light is detected. In the imaging step, a tomographic image of the object is formed based on the detection results of a plurality of the interference lights sequentially obtained in the detection step according to the scanning.