The present invention provides a waterproof box which has small size, high workability in its assembling, and high waterproof character. The waterproof box includes a body including a peripheral body wall which has an annular convex rim defining an opening, and a first fulcrum portion which is provided on the peripheral body wall; and a cover covering the opening and including a peripheral cover wall which has an annular chase defined by a inner wall and an outer wall and engaged with the annular convex rim, and a second fulcrum portion which is provided on the peripheral cover wall and engaged with the first fulcrum portion so that the cover rotates about the fulcrum portions. A height of a first edge of the inner wall corresponding to the second fulcrum portion is lower than that of a second edge of the inner wall adjacent to the first edge.