An optical tomographic imaging apparatus capable of acquiring a two-dimensional or/and three-dimensional tomographic image having higher SNR and quality by cancelling phase change caused by birefringence of a sample in average processing using a predetermined kernel region, and calculating a global phase difference of each pixel in the kernel. The optical tomographic imaging apparatus includes a processing unit configured to: set a predetermined kernel to a B scan image or/and C scan image (volume data) acquired corresponding to a Jones matrix； model the Jones matrix of each pixel in the set predetermined kernel by using one or more unitary matrices to calculate a relative global phase of each pixel； and cancel the calculated relative global phase in each pixel in the predetermined kernel to average each element of the Jones matrix in the predetermined kernel.
