PURPOSE: To enable automatic change of band saw blade by turning upper and lower saw blade carriers, expanding and overlapping them, transferring a band saw blade trained over a saw blade attaching magazine to drive and driven wheels and transferring the band saw blade trained over the drive and driven wheels to a saw blade recovering magazine.

CONSTITUTION: When a band saw blade is attached, saw blade carriers 113a, 113b are expanded to attach a saw blade magazine having the band saw blade 3 attached thereto to drive and driven wheels 19, 21 and then overlap the saw blade carriers so that the saw blade magazine is separated from the drive and driven wheels 19, 21 for attaching the band saw blade 3. Next, in the recovery of the band saw blade, the saw blade carriers 113a, 113b are overlapped to attach the saw blade magazine to the drive and driven wheels 19, 21 and then expand the saw blade carriers for recovering the band saw blade 3.