Traditional chairs are stored by stacking or folding. It is a waste of space and unsightly. The present invention improved the structure of the chair to achieve the purpose of saving storage space. The space-saving chairs are composed of a group of components including seats, legs, and a storage space. The seats are for people sitting. The storage space is formed among chair legs. Each chair can be placed into the storage space from the side of another chair. Six chairs can be combined into a cube perfectly.