Recently, deep learning has made significant progress in image denoising. However, most of existing deep learning based methods are purely dataādriven, without considering the knowledge of image denoising. Moreover, the parameters of deep denoising network are not explainable. According to these issues, this paper proposes a deep side group sparse coding network for image denoising, named a side group sparse coding (SGSC)āNet. First, SGSC model for image denoising by exploiting prior information regarding the group sparse coefficients consistency is developed. Specifically, the side information is constructed as the weighted combination of intermediate estimations, and updated iteratively. Then, the optimisation solution of SGSC model is turned into a deep neural network using deep unfolding, that is, SGSCāNet. The computational path of SGSCāNet fully follows the iterations of optimisation solution, and consequently the network parameters are interpretable. Furthermore, the design of SGSCāNet employs the insight of SGSC denoising model. The experimental results on wellāknown datasets quantitatively and qualitatively demonstrate that SGSCāNet is competitive to existing deep unfoldingābased and typical deep neural networkābasedĀ methods.