To provide a method of manufacturing a laminate tube which can be formed into a tubular container which excels in external appearance and strength and of which seal portion does not have an air gap and does have the same thickness as other portions.

A laminate sheet 8 comprising at least two layers of thermoplastic resin layers 4, 5 and an intermediate layer 6 which is sandwiched between the two layers of the thermoplastic resin layers 4, 5 and has a higher melting point than the two layers of the thermoplastic resin layers 4, 5 is formed into a tubular shape, and its end faces 8a, 8b are opposingly arranged with a gap t' in between. Then, the end faces 8a, 8b are mutually heat-welded by heating them from both sides of the laminate sheet 8 at a temperature which is not less than the melting point of the thermoplastic resin 4, 5 and is not more than the melting point of the intermediate layer 6.