To provide a bar cutting device which can reduce labor required for the replacement of a worn cutting blade.

A pipe cutting device 1 for continuously cutting a bar 100 by a circular cutting blade 50 includes a nut runner 6 which fixes the cutting blade 50 to a drive shaft 52a and releases the fixing, a replacement arm 60 which performs the replacement of the cutting blade 50 by the swing of the tip thereof having a chuck 61 along a surface crossing at a right angle to the extension line of the drive shaft 52a, a stock bar 67 capable of holding a plurality of cutting blades 50a for replacement in a stacked manner, and a stock bar 68 capable of holding a plurality of used cutting blades in a stacked manner. After the worn cutting blade 50 is unfixed by the nut runner 65, and transferred to the stock bar 68 by the replacement arm 60, the cutting blade 50a of the stock bar 67 is taken out by the replacement arm 60, inserted into the drive shaft 52a, and fixed by the nut runner 65, thus completing replacement work.