A band saw is disclosed to includes a holder frame, which is movable along two vertical guide rods above the machine base and holds a saw blade and a saw blade driving mechanism, a nut fixedly provided at the top of the holder frame, a vertical motor mounted on a connecting frame at the top of the guide rods, and a screw rod threaded into the fixed nut and rotatable by the vertical motor to move the holder frame along the guide rods to the desired elevation.