To provide a tool abnormality detecting device which eliminates complicated procedures and accurately detects the abnormal state of a tool, and to provide a tool abnormality detecting method, a program, and a recording medium.

The tool abnormality detecting device is comprised of a mean value comparative operating section 33, an oscillation component comparative operating section 36, and an abnormality determining section 37. The mean value comparative operating section 33 sets a threshold mean value TMTa based on a mean value MTa of cutting torque mean values Tqa1 to Tqa6 of torque sensors 15a to 15f, and standard deviation σTa, and determines whether or not any of the cutting torque mean values Tqa1 to Tqa6 is in excess of the threshold mean value TMTa. The oscillation component comparative operating section 36 sets a threshold power spectral value TMPS based on a mean value MPS of power spectral values PS1 to PS6 in the vicinity of a predetermined oscillation component of the cutting torques Tq1 to Tq6, and standard deviation σPS, and determines whether or not one of the power spectral values PS1 to PS6 is in excess of the threshold power spectral value TMPS. If one of the determination results of the mean value comparative operating section 33 and the oscillation component comparative operating section 36 is positive (YES), the abnormality determining section 37 determines that one of drills undergoes an arnomality.