To provide a device and method for rolling a steel tube which are excellent in not only tube polishing but also tube expanding capability without slowing down rolling speed than that in the conventional manner.

In the rolling device for the steel tube provided with a pair of two upper and lower rolls and a plug which is inserted into the hole on a stock tube which is passed through between the rolls and with which the tube stock is pressed, the rolls are taken as a combination type of a cylindrical body on the inlet side and a truncated conical body on the outlet side and the plug is taken as a taper plug whose surface is inclined in the direction of the tip.