To provide a roll stand for forming a metallic tube which is advantageous in the aspect of economy and storaging property by making both size and weight of a machine to be possessed as a spare smaller than those of a conventional one.

The roll stand for forming is composed of an outer stand 44 in which a distributing gear mechanism for distributing and transmitting driving torque from a roll driving source to rolls is incorporated and which is usable in common and inner cassette 40 in which the rolls, roll shafts 29a, 30a, 31a, roll bearings, or the like in accordance with the size of a formed tube are incorporated. The inner cassette 40 is freely mounted to and dismounted from the outer stand 44 and the batch change of the rolls is possible.