Abstract: A rotatable securing device for a tool box has a casing, a securing unit and a locking unit. The casing has a locking recess, the locking recess is provided with an opening at a middle area, and a plurality of engaging grooves and a first contacting face are evenly disposed on a circumference of the locking recess. The securing unit respectively has a supporting surface at an upper end and a lower end, and a fastening rib respectively disposed at two sides of the two supporting surfaces. The locking unit is a flat disk; the locking unit has an engaging face corresponding to the fastening rib, a plurality of positioning protrusions disposed on its edge, at least one the elastic slot adjacent to the positioning protrusion, and a second contacting face for in contact with the supporting surface.