PURPOSE: To obtain a bimetallic tube of an optional shape and dimension whose inner and outer layers are made of an optional material with a simple equipment with extending the outer tube by reducing its diameter and with adhering it closely to the outer face of the inner tube, by inserting an inner tube into the outer tube of which tube end part was worked with shrinking its diameter in advance and by performing a drawing work in the axial direction via a grasping jig of the end of the outer tube.

CONSTITUTION: Both end parts of the outer tube Po is subjected to a diameter shrinking work to the inner diameter nearly equivalent to the outer diameter of an inner tube Pi by a press work, etc. after forming a projecting part 3 with a buildup welding on the outer tube Po in case of a conventional steel pipe being taken as an outer tube Po and a stainless steel pipe as the inner tube Pi, for instance. When the drawing work in the tubular shaft core direction is made on the outer tube Po with a drawing work device then with inserting the inner tube Pi into the outer tube Po thereof and with installing a halving type clamp jig 2 to the respective diameter shrinking part of the outer tube Po, the outer tube Po starts to extend and to shrink the diameter from around the center of the axial direction. The diameter shrinking part is widened gradually toward both end parts after the inner face thereof being brought into contact with the outer face of the inner tube Pi and finally the contact condition is obtd. over the whole length.