1. A method of reducing noise in a medical image, the method comprising: a step of estimating the amount of noise in at each pixel position of an image by using a look-up table that is previously stored in order to suppress noise in the medical image; a step of extracting a first signal structure direction and a first signal coherence at each pixel position; a step of obtaining a first anisotropic smoothing filter kernel that reflects the extracted signal structure direction and the signal coherence; a step of obtaining an anisotropic-smoothed intermediate image by performing filtering using the first anisotropic smoothing filter kernel; and a step of extracting a second signal structure direction and a second signal coherence at each pixel of the anisotropic-smoothed intermediate image, and obtaining a second anisotropic filter kernel that reflects the second signal structure direction and the second signal coherence, and performing filtering on an original image by applying an additional weight that reflects the estimated amount of noise in the position of each pixel to surrounding pixels within a range of the filter kernel.