There is provided a method of reducing noise in a medical image while maintaining structure characteristics within the medical image. The method of reducing noise in the medical image includes: a step of estimating the amount of noise at each pixel by using a look-up table that previously stores physical properties of an image capturing device; a step of calculating a structure direction and a signal coherence at each pixel; a step of performing anisotropic smoothing by using an anisotropic smoothing filter kernel that reflects the structure direction and the signal coherence; and a step of obtaining a structure direction and a signal coherence from an image on which the anisotropic smoothing is performed, obtaining an anisotropic smoothing filter kernel that reflects the obtained structure direction and the signal coherence, and performing filtering that reflects statistical properties of the estimated amount of noise.