PURPOSE: To raise the excavating function of a rock cutter bit by reducing the resistance of the tip of excavator by a method in which a soil-carrying hole is formed in the bottom of the main cutter row and communicated to a soil discharge pole.

CONSTITUTION: When an excavator A is advanced while turning a cutter bit 1, rock-bed is excavated by the main cutters of the bit 1. The excavated soil and crushed rock are automatically directed into the hollow 7 of the bit 1 through the soil-carrying hole of the main cutter row bottom, where the rock and soil are carried by a pressure fluid introduced from the tip pressure fluid supply hole 5 of the bit 1 to the inside of the excavator through the discharge port G of the excavator A from the rear end discharge hole.