PURPOSE: To reduce an idle time so as to improve cutting efficiency by providing a photoelectric switch for emitting light parallel to a saw blade and a groove where the photoelectric switch becomes lower than the upper surface of a work table.

CONSTITUTION: At least photoelectric switches 31F, 31B go into a groove formed on the upper surface of a work table 27 during the cutting, and the cutting is performed without any problem. And photoelectric switches 31F and 31B, 33F and 33B are provided respectively under a drive-side saw blade guide member 17 and a driven-side saw blade guide member 19 parallel to a band saw blade 11, so that the rising and lowering ends of the band saw blade 11 can be detected immediately after they leave a work W, that is, the cutting is completed. As a result, since the rise of the band saw blade 11 or a movement toward a vice device is immediately carried out, a useless idle time is reduced so that cutting efficiency can be improved.