A combination safe deposit box includes a first box shell and a second box shell fastened together to define a deposit space, a plurality of side guard frames and corner guard frames fastened to and covered on the abutted area between the first box shell and the second box shell, a rim frame affixed to the front side of the first box shell and a second box shell and capped on two distal ends of the connected series of the side guard frames and corner guard frames, and a door panel hinged to one side of the rim frame and adapted to close the deposit space.