A horizontal band saw machine that cuts a workpiece stopped on a feed direction while feeding an endless band saw blade circularly, the machine comprising: a base; a vise mechanism that is provided on a downstream side of a cutting position on the base, and includes a pair of jaws (9, 11) that faces to each other along a width direction perpendicular to the feed direction to clamp the workpiece, one of the pair of jaws (9, 11) being provided on one side with respect to the cutting position along the width direction, and another thereof being provided movably on another side along the width direction; a cutting head that is provided on the base vertically-movably, and extends in the width direction; a pair of saw blade wheels (37, 39) that are provided rotatably on the cutting head, and distanced from each other along the width direction; the band saw blade that is looped over the pair of saw blade wheels (37, 39); a saw blade guide mechanism having a pair of saw blade guides (45, 47) that are suspended from the cutting head between the pair of saw blade wheels (37, 39), saw blade inserts (49, 51) being provided at respective lower ends of the pair of saw blade guides (45, 47), one of the pair of saw blade guides (45, 47) being provided on the one side, another thereof being provided on the other side movably in the width direction, and the band saw blade being twisted between the pair of saw blade guides (45, 47) to orient saw teeth thereof downward; a contact guide that is attached to the other of the pair of jaws (9, 11), and extends vertically; characterized by a coupling bracket of which base end is connected to the other of the pair of saw blade guides (45, 47), and that is extended in the width direction to locate a distal end thereof below the other of the pair of saw blade wheels (37, 39); and a follower member that is provided at the distal end of the coupling bracket, and slidably contacts with the contact guide, wherein the contact guide and the coupling bracket are configured to move the other of the pair of saw blade guides (45, 47) toward the one side in the width direction until the follower member contacts with the contact guide by feeding the band saw blade circularly in a state where the band saw blade is clamped by the saw blade insert of the other of the pair of saw blade guides (45, 47). a base; a vise mechanism that is provided on a downstream side of a cutting position on the base, and includes a pair of jaws (9, 11) that faces to each other along a width direction perpendicular to the feed direction to clamp the workpiece, one of the pair of jaws (9, 11) being provided on one side with respect to the cutting position along the width direction, and another thereof being provided movably on another side along the width direction; a cutting head that is provided on the base vertically-movably, and extends in the width direction; a pair of saw blade wheels (37, 39) that are provided rotatably on the cutting head, and distanced from each other along the width direction; the band saw blade that is looped over the pair of saw blade wheels (37, 39); a saw blade guide mechanism having a pair of saw blade guides (45, 47) that are suspended from the cutting head between the pair of saw blade wheels (37, 39), saw blade inserts (49, 51) being provided at respective lower ends of the pair of saw blade guides (45, 47), one of the pair of saw blade guides (45, 47) being provided on the one side, another thereof being provided on the other side movably in the width direction, and the band saw blade being twisted between the pair of saw blade guides (45, 47) to orient saw teeth thereof downward; a contact guide that is attached to the other of the pair of jaws (9, 11), and extends vertically; characterized by a coupling bracket of which base end is connected to the other of the pair of saw blade guides (45, 47), and that is extended in the width direction to locate a distal end thereof below the other of the pair of saw blade wheels (37, 39); and a follower member that is provided at the distal end of the coupling bracket, and slidably contacts with the contact guide, wherein the contact guide and the coupling bracket are configured to move the other of the pair of saw blade guides (45, 47) toward the one side in the width direction until the follower member contacts with the contact guide by feeding the band saw blade circularly in a state where the band saw blade is clamped by the saw blade insert of the other of the pair of saw blade guides (45, 47).