An NR coefficient (Kf) is calculated on the basis of a representative value (Pm) of a pixel of interest and a low-pass filtered value (La-Ld) nearest to the representative value (Pm) of the pixel of interest among a plurality of low-pass filtered values filtered one-dimensionally in different directions in an input image, and the pixel value of the pixel of interest and a value output by a two-dimensional low-pass filter (25) are weighted by the NR coefficient (Kf) and added (36). The representative value of the pixel of interest may be, for example, a median value obtained by filtering the current frame and a past frame in the time axis direction. The image processing device reduces noise without lowering resolution.