To integratedly clamp and fix a storage body and a lid body by providing a clamping piece capable of attaching a string capable of being clamped around a bottom side and opposite sides of the storage body and an upper surface of the lid body on the side of the storage body, and clamping and attaching one end part to the other end part of the string.

Two strings 12 are formed on right and left sides of a storage body 1, and fixed to the sides by screws 13. The strings 12 are single, and of the length capable of binding four sides including the storage body 1 around its bottom side, opposite sides, and an upper surface of a lid body 8. A metal fitting body 14a provided with a holding body 14b in a turnable manner is fitted to one end open of the strings 12. The holding body 14b is turned against a spring member 14d to open an insertion part 14e, and the other end part of the strings 12 is inserted and pulled to be tightened. In this condition, the holding body 14b is released, and the strings 12 are held between the holding body 14b and a holding part 14c by the spring pressure of the spring member 14d. The storage body 1 and the lid body 8 are integratedly clamped with and fixed to each other.