A neutrosophic set (NS), a part of neutrosophy theory, studies the origin, nature, and scope of neutralities, as well as their interactions with di r erent ideational spectra. The neutrosophic set is a general formal framework that has been recently proposed. However, the neutrosophic set needs to be specified from a technical point of view. Now, we apply the neutrosophic set into image domain and define some concepts and operators for image denoising. The image G is transformed into NS domain, which is described using three membership sets: T, I and F. The entropy of the neutrosophic set is defined and employed to evaluate the indeterminancy. A new operation, beta-median-filtering operation, is proposed to decrease the set indeterminancy and remove noise. We have conducted experiments on a variety of noisy images using di r erent types of noises with di r erent levels. The experimental results demonstrate that the proposed approach can remove noise automatically and e r ectively. Especially, it can process not only noisy images with di r erent levels of noise, but also images with di r erent kinds of noise well without knowing the type of the noise, which is the most dificult task for image denoising.