A height access device enables motorized access to the driving station of a tower crane atop a mast formed of superposed mast elements. It includes a lift cabin installed inside the mast of the crane and movable vertically along the mast. The height access devices further includes a working platform positioned above and separably connected to the lift cabin. A coupling device provides a non-permanent connection of the working platform to the lift cabin and immobilizes the working platform relative to the mast at a required height. The height access device enables the crane driver to ascend and descend with the lift cabin alone when disconnected from the working platform and with the lift cabin and working platform together, particularly during the assembly and dismantling of the mast.