To prevent lowering of product quality by preventing cutting oil from entering a product gap (gap between square steel pipes) in the case of cutting bound square steel pipes.

A cutting oil spreader 10 for spreading cutting oil on the band sawing cutting edge 1 is provided on a cut-out position (A part) of a circulating band saw cutting edge 1, and an air sprayer (cutting oil removing device) 21 for removing cutting oil adhering to the band sawing cutting edge 1 is provided in a cut-in position (B part) of the band sawing cutting edge 1. In the case of cutting the bound square steel pipes (cut material) 5 formed by binding plural coated square steel pipes (cut material) 5, the bound square steel pipes 5 are cut by the band sawing cutting edge put in the dry state or little quantity of cutting oil adhesion, so that cutting oil can be prevented from entering the gap between the bound products to prevent a coated fil from being separated or discolored by the cutting oil. Soil of the product due to metal chip can be prevented. Even if metal chips are accumulated in the vicinity of the section of the product in cutting, they can be easily removed by compressed air or the like because of dry state.