To provide a sandwich structure which can be easily processed.

As the sandwich structure 80 has such a sandwich structure that has a closed-cell foamed plastic material 85 and a honeycomb core 81 as core materials 86 and is pinched by face plates 83 and 84 consisting of a composite material in which an inorganic fiber with an affinity with water is used as a reinforcing fiber, water does not penetrate inside. In this sandwich structure, the foamed plastic material 85 is used as the core material in the part where plate pressure is largely changed and the honeycomb core 81 is used as the core material in the part where the plate pressure is mildly changed. It is possible thereby to facilitate the processing.