A tunnel boring machine , comprising: a main body ; a cutter head that is disposed in front of the main body and is rotatable with respect to the main body ; a plurality of disc cutters rotatably mounted on the cutter head , each of the disc cutters including a cutter ring that is exposed to a front surface of the cutter head while exposed to a back surface of the cutter head , the cutter ring including a cutting edge part ; and an acquisition unit that is disposed behind the plurality of disc cutters to acquire cutting edge position data indicating a position of the cutting edge part , characterized by further comprising: a discrimination unit for discriminating which one of the plurality of disc cutters is the disc cutter cutting edge position data of which is acquired by the acquisition unit ; and a calculator for calculating a wear amount of the cutting edge part of the disc cutter discriminated by the discrimination unit based on the cutting edge position data of the discriminated disc cutter , wherein the discrimination unit detects distance from a center of the cutter head to the cutting edge part of each of the plurality of disc cutters , or detects a rotation angle of the cutter head with respect to the main body to discriminate a disc cutter among the plurality of disc cutters . a main body ; a cutter head that is disposed in front of the main body and is rotatable with respect to the main body ; a plurality of disc cutters rotatably mounted on the cutter head , each of the disc cutters including a cutter ring that is exposed to a front surface of the cutter head while exposed to a back surface of the cutter head , the cutter ring including a cutting edge part ; and an acquisition unit that is disposed behind the plurality of disc cutters to acquire cutting edge position data indicating a position of the cutting edge part , characterized by further comprising: a discrimination unit for discriminating which one of the plurality of disc cutters is the disc cutter cutting edge position data of which is acquired by the acquisition unit ; and a calculator for calculating a wear amount of the cutting edge part of the disc cutter discriminated by the discrimination unit based on the cutting edge position data of the discriminated disc cutter , wherein the discrimination unit detects distance from a center of the cutter head to the cutting edge part of each of the plurality of disc cutters , or detects a rotation angle of the cutter head with respect to the main body to discriminate a disc cutter among the plurality of disc cutters . a discrimination unit for discriminating which one of the plurality of disc cutters is the disc cutter cutting edge position data of which is acquired by the acquisition unit ; and a calculator for calculating a wear amount of the cutting edge part of the disc cutter discriminated by the discrimination unit based on the cutting edge position data of the discriminated disc cutter , wherein the discrimination unit detects distance from a center of the cutter head to the cutting edge part of each of the plurality of disc cutters , or detects a rotation angle of the cutter head with respect to the main body to discriminate a disc cutter among the plurality of disc cutters . <EOS>