Affords large-diametric-span AlN crystals, applicable to various types of semiconductor devices, with superior crystallinity, a method of growing the AlN crystals, and AlN crystal substrates. The AlN crystal growth method is a method in which an AlN crystal (4) is grown by vapor-phase epitaxy onto a seed crystal substrate (2) placed inside a crystal-growth compartment (24) within a crystal-growth vessel (12) provided within a reaction chamber, and is characterized in that during growth of the crystal, carbon-containing gas is supplied to the inside of the crystal-growth compartment (24).