PURPOSE: To prevent the inside surface of tube from generating oxidized scale by applying liquid glass lubricant on the inside surface of the tube of compound material before heating in the manufacture of a clad steel tube by skew rolling.

CONSTITUTION: At the time of manufacturing the clad steel tube which is made by skew rolling that the tube 10 of compound material which consists of high corrosion-resisting alloy such as a stainless steel and nickel base or iron base superalloy is fitted to the side of the inside surface of a tube made of a base metal of carbon steel and a center member 21 is inserted into the tube 10 of compound material after heating it to a rolling temp., the liquid glass lubricant is applied to the inside surface of the tube 10 of compound material before heating. In this way, oxidized scale which is generated on the inside surface of the tube stock is prevented and high lubricating performance is displayed regardless of whether the center member 21 is preheated or not and high or low rolling reduction ratio.