Abstract: A method of cutting a steel pipe or/and junction joints in form of a steel pipe pile or interlocked steel pipe pile used, for example, in formation of an underwater foundation support, after it is completed. The method is executed in accordance with a non-contact technique or the combination of a contact technique and a non-contact technique. The method is carried out by a plasma arc cutting device or the combination of a contact type cutting grinder and non-contact type cutting device, which can effectively cut the steel pipe, with no possibility of biting of the cutting edge in the cut gap of the steel pipe.