PURPOSE: To obtain a finished tube having excellent shape of inner surface without wrinkles by a reducing rolling method for welded tube with which a welded tube whose bead is cut is reducing rolled.

CONSTITUTION: At two intersecting points P, Q of a circular arc 3 in the cutting part where the bead on the inner surface of the welded tube 1 is cut and the inner peripheral circle 4 of the welded tube 1, crossing angles A, B between the circular arc 3 and the inner peripheral circle 4 at the respective intersecting points P, Q are set smaller than 60° and the difference of these crossing angles A and B is made smaller than 30°, and the welded tube 1 is reducing rolled.