To simplify the reclosing manipulation of a package, by providing a reclosable structure having a preventive function against turning back arranged in mutually engaging corner of the container side walls.

In a package 10, lips 32, 36 of the container and the cover are arranged at the corners 24, 38 of the container and the cover corresponding thereto respectively. And extended parts 46, 48 of the container and the cover for fixing and engaging the cover having a coincident shape to correspond thereto. The extended parts 46, 48 of the container and the cover have a little different size from each other and when these are engaged, an appropriate engaging force is generated. For instance, either of the extended parts of the container and the cover can be elongated for instance during the engaging motion and also the elongation can be restored. The inside food is hermetically sealed at the lips 32, 36 with a substantial inert gas to form an air package, the food is surrounded and protected by the inert gas until the package is opened.