PURPOSE: To stably stack up plastic containers with less labor by attracting and connecting the adjacent plastic containers together by the attraction between N S poles of permanent magnets.

CONSTITUTION: Plastic containers 7 are provided with permanent magnets 12 on both side faces, and when the plastic containers 7 are horizontally arranged and stacked up inn multi-stages, tire plastic containers 7 are arranged so that the N poles and S poles of the permanent magnets 12 attached to the adjacent plastic containers 7 face each other. Thereby, as the adjacent plastic containers 7 are connected together by the attraction between the N poles and S poles of the permanent magnets 12 and the horizontal stability is improved, the plastic containers 7 can be stably stacked up in multi-stages when the plastic containers 7 are horizontally arranged and stacked up in multi-stages.