A method of adaptively attenuating image-noise according to a degree of motion of an image signal and an apparatus therefor are provided. An input image signal is filtered in a spatial area to attenuate noise of the input image signal. The input image signal is filtered in a temporal direction to attenuate noise of the input image signal. A degree of motion of the input image signal is extracted each predetermined period. An image signal whose noise is spatially attenuated is mixed with an image signal whose noise is temporally attenuated according to the degree of motion of the input image signal and a mixed image signal is output.