To enhance excavating force by generating a crack in rock-bed by a laser beam, by installing an excavating blade in the tip part, and irradiating the laser beam forward more than the excavating blade by rotating the excavating blade.

A through hole 1a is bored in the central part of an excavating blade 1, an optical fiber 4 is inserted into the through hole 1a, the optical fiber 4 is made unentangling, and the optical fiber 4 is connected to a laser transmitter 5. The excavating blade 1 is contacted with rock-bed, and is pressed to the rock mass while rotating the excavating blade 1 by transmitting a laser beam 6 from the laser transmitter 5. A crack is generated in the rock-bed by using the laser beam 6, and the excavating blade 1 bites into the rock-bed to enable excavation as well as to increase excavating force. Therefore, a crack is generated by the laser beam 6, excavation is performed by rotation of the excavating blade 1, and even in hard rock-bed such as grinite, progress of work can be quickened by using the large excavating blade 1.