To pile up containers where a structure is simple and inexpensive by allowing an inner cylinder to accept the bottom part of the containers to be piled up in sealed state in the double cylindrical structure consisting of inner and outer cylinders where a side wall part is connected by a top part.

A dead weight pressure given by a bottom part 12 of a storage container 1 compresses water 13a in a double cylindrical structure that is confined in sealed state by a sealing material 23 of a spacer 20 and an outer- periphery surface 1a of the container 1, thus securing a sealing property at an initial stage with the sealing material 23. As the container 1 is gradually lowered, its dead weight is converted to the compression pressure of the water 13a being entrapped in a structure, thus pressing an upper edge flex part 22a of a side wall part 22 of the spacer 20 toward an outer-periphery surface 1a of the container 1 and firmly placing the spacer 20 and the container 1 due to the placement force of the container 1. The container 1 has a flange part 1b at an upper part and a disk-shaped projecting part 1c projects upward from the center of the flange part 1b. On the other hand, a bottom part 21 of the spacer 20 is flexed upward, demarcates a recessed part 21a, and accepts the projecting part 1c.