PURPOSE: To improve efficiency, yield and quality by specifying a surface temp. of a blank pipe, rolling ratio, roll tilt angle and roll cross angle in the stage of forming a seamless pipe of a titanium material by two rolls skew rolling.

CONSTITUTION: The seamless pipe is formed by extending rolling a hollow blank pipe of pure Ti or Ti alloy using the two rolls skew rolling mill. In this case, when the surface temp. T1 of the hollow blank pipe 13 at the entrance of main rolls 11, 11' for extending rolling is 650W800°C, the rolling ratio is set ≤2.8, when the temp. T1 is 800W1,150°C, the rolling ratio is set ≤3.2. Furthermore, the extending rolling is performed in the states where the roll tilt angle βand the roll cross angle γ are 4°≤β≤16°, 6°≤γ+β respectively. When the temp. T1 is <650°C, a miss roll, seizure, flaw are generated and when the temp. T1 is >1,150°C, defects are generated on the inner and outer surfaces of the pipe. When the rolling ratios are other than said values, the seizure, faulty biting, faulty passing through, etc., are generated. When the angle β is <4°, the defects on the inner and outer surfaces of the pipe are generated and an efficiency is lowered, and when it is >16°, the faulty biting and faulty passing through, etc., and seizure are generated. When the γ+β is <6°, the quality of the inner surface of the pipe is deteriorated.