Recently, carbon fiber-reinforced plastic (CFRP) has been attracting much attention in various industries because of its beneficial properties such as excellent strength, modulus per unit density, and anti-corrosion properties. However, there are several issues in its application to various fields. Severe tool wear issues in its machining have been noted as one of the most serious problems because it induces various serious machining failures such as delamination and splintering. In this regard, timely tool replacement is essential for reducing the influence of tool wear. In this study, tool wear, especially flank wear, in the CFRP drilling was investigated and monitored. First, the reproducibility of tool wear under the same machining condition was experimentally evaluated. And it is demonstrated that tool wear may remarkably differ even though the same machining condition is applied to the tools. Then, tool wear monitoring based on the feed motor torque was applied to the detection of tool life ending in the CFRP drilling process. Consequently, it was demonstrated that the average and maximum detection error of the tool life end were less than 7 and 14%, respectively.