To provide a tube forming device capable of bending a forming part of a tube halfway.

Plural forming rollers 27, which reduces a tube 42 in the radial direction by rotating around a prescribed rotation axis on the same circle loci, are arranged. The tube is held to a tube holding fixture 33. A rotation means (rotation table 50), which moves the tube holding fixture 33 along a circular arc around the forming part of the tube 42 or its neighborhood in the horizontal direction, is arranged.