Abstract: A floor safe engageable in and through a rectangular opening in a wood floor and between opposing sides of laterally spaced joists supporting the floor, said safe including an upwardly opening rectangular box-like body with a horizontal bottom wall and flat vertical side walls slidably arranged in said opening in the floor and between said joists with opposite side wall in substantial flat bearing engagement with said sides of the joists; fastening means fixing the body to the joists including apertures in said opposite side walls and elongate headed fasteners engaged through the openings and into the joists from within the body, a flat horizontal cover plate in overlying supported engagement with the top of the body and having a top surface substantially flush with the floor; said cover plate has a central vertical access opening, releasable coupling means securing the cover plate in tight engagement with the body and including laterally projecting brackets on said side walls between the ends thereof, vertic