A tool holding module comprises a fixture seat and a tool rod. The fixture seat has a first outer surface on an external wall, a first top surface on one end, and a fixture head is located on the same end. The fixture head has a second outer surface on an external wall and a second top surface on one end. The internal wall of the tool rod has first and second inner surfaces respectively corresponding to the first and second outer surfaces, and has first and second butting surfaces respectively corresponding to the first and second top surfaces. The tool rod and fixture seat are connected to enfold the fixture head. The security of the tool holding module is enhanced via close contact of the first outer and inner surfaces, the second outer and inner surfaces, the first top and butting surfaces, the second top and butting surfaces.