To provide a tower crane support device capable of reducing a load to a beam or a column in a structure being constructed.

This tower crane support device 1 is used to support and fix a tower crane 800 for performing floor climbing to the structure. It is provided with a base receiving frame 1A to support the tower crane 800 around a lower end part of a mast 2B, and a horizontal force support body 1B to support the tower crane 800 at an intermediate part of the mast 2B for mainly receiving horizontal force. Since the horizontal force support body 1B is thus provided, moment and the horizontal force can be greatly reduced among three loads of a vertical load, the horizontal force, and the moment. The load applied to the beam 56 or the column close to the base receiving frame 1A can thus be greatly reduced.