According to the invention, the box for packaging an object, comprising at least two upper edges, comprising: lateral walls, a delimiting bottom, with the lateral walls, an internal volume able to receive said object, and a moving cover in relation to at least one of said lateral walls, so as to be able to occupy at least one closed position and one open position, in which said receiving volume is respectively closed and open, characterized by the fact that the cover comprises, on its internal face oriented toward the receiving volume, at least two main flaps that are arranged opposite each other and that are designed to be applied respectively against the upper edges of said object, when the cover occupies the closed position.