An apparatus and a method for coating an inner wall of a metal tube are provided. The apparatus for coating an inner wall of a metal tube includes mounting posts on which both end openings of a metal tube are mounted and configured to block the inside of the metal tube from the ambient air so that a pressure in the metal tube is adjustable by the vacuum exhaust and inflow of process gases, a sputtering target metal tube installed inside the metal tube coaxially with the metal tube, a pulse electromagnet installed around an outside perimeter of the metal tube coaxially with the metal tube to apply a pulse magnetic field in an axial direction of the metal tube, an electromagnetic pulse power supply unit configured to apply pulse power to the pulse electromagnet, and a sputtering pulse power supply unit configured to synchronize a negative high-voltage pulse with the pulse power applied to the pulse electromagnet and apply to the sputtering target metal tube.