1. A method for reducing noise in a tomographic image, comprising: acquiring a first tomographic image based on a spectrum interference signal output from a detector of a swept source optical coherence tomography device; acquiring a phase of a noise component signal, the noise component signal being provided as a signal corresponding to a noise component of the first tomographic image and included in the spectrum interference signal output from the detector of the swept source optical coherence tomography device; correcting a phase deviation of the spectrum interference signal based on the acquired phase; and reducing the noise component signal in the spectrum interference signal in which the phase deviation has been corrected to acquire a second tomographic image.