To provide a method of cutting a metal tube capable of inhibiting a generation of burr at both tube ends of a cut portion clamping a blade in a metal tube and inhibiting an abrasion of the blade.

In this method of cutting metal tube, when a metal tube P is cut using a blade, the blade 2 and the metal tube P are approached at a constant speed and a cutting is started from one side of the metal tube P while a neighborhood clamping a cutting position of the metal tube P is retained at the same height as a conveying height by a placing base 3. When the blade is relatively moved from an inner surface at the other side of the metal tube P to a position of 2-5 times in comparison with a thickness t of the metal tube P, a relative movement speed of the blade and the metal tube P is increased 1.05-1.30 times than the times of cutting starting.