There is provided a drilling rig for use on a drilling platform, comprising a drilling mast having at least two segments and a feed carriage, said drilling mast being adapted to be constructed in such a manner that at least one segment is displaced upwardly by means of the feed carriage. A mounting method in accordance with the invention for a drilling mast having at least two segments comprises the following steps: fixing of a feed carriage, providing of a mast segment below the feed carriage, and displacing the mast segment upwardly by means of the feed carriage. Due to this, additional auxiliary devices for constructing the drilling mast are not required, and space may be saved.