Deep neural networks (DNNs) usually demand a large amount of operations for real-time inference. Especially, fully-connected layers contain a large number of weights, thus they usually need many off-chip memory accesses for inference. We propose a weight compression method for deep neural networks, which allows values of +1 or -1 only at predetermined positions of the weights so that decoding using a table can be conducted easily. For example, the structured sparse (8,2) coding allows at most two non-zero values among eight weights. This method not only enables multiplication-free DNN implementations but also compresses the weight storage by up to x32 compared to floating-point networks. Weight distribution normalization and gradual pruning techniques are applied to mitigate the performance degradation. The experiments are conducted with fully-connected deep neural networks and convolutional neural networks.Index Terms-Deep neural networks, weight storage compression, structured sparsity, fixed-point quantization, network pruning. The hardware for inference contains a small look-up table for decompressing the code, but the procedure is very simple and deterministic. The data-path needs a reduced number of arithmetic units because most of the weights are pruned to zero. The indexing addresses can be easily interpreted to corresponding weights. Also, this method has a good scalability because the look-up table size is independent of the network complexity. However, training the structured sparsity network is more difficult than optimizing the conventional ternary valued networks. We use batch normalization and weight normalization techniques to mitigate the performance degradation. Also gradual pruning technique is applied for a large-sized network to improve the performance. The proposed scheme was evaluated on FCDNN, VGG-9, and AlexNet and obtained the compression rate between x23 and x32. The rest of this paper is organized as follows. Section II