A frequency characteristic measurement device that measures the frequency characteristic of a measurement target includes: a multi-sine signal generation unit that generates a multi-sine signal; a sweep sinusoidal wave generation unit that generates a plurality of sweep sinusoidal waves; an input signal switching unit that selects any one of the multi-sine signal and the sweep sinusoidal waves so as to input the selected one to the measurement target; a data acquisition unit that acquires, at a predetermined sampling frequency, sampling data of an input signal which is input to the measurement target and sampling data of an output signal which is output from the measurement target; and a characteristic calculation unit that calculates a frequency characteristic including the gain and the phase of the input and output signals in the measurement target from the sampling data of the input and output acquired.

A diagnostic apparatus includes a receiving unit to receive context information defining an operation of a tool of a machine, rotation information of a spindle, tool information, and a detection result of a time-varying physical quantity generated by the tool; a frequency analysis unit to frequency-analyze the detection result; a range setting unit to set a frequency range; a bandwidth setting unit to set a bandwidth of a noted frequency band in the frequency range; a band pass filter setting unit to set a band pass filter using center frequencies and the bandwidth; a feature information extraction unit to extract feature information from the detection result using the band pass filter and a frequency analysis result of the detection result; and a determining unit to determine a machining state using the feature information. The center frequencies are set using the rotation information, the tool information, and the frequency range.

A frequency characteristic measurement device that measures the frequency characteristic of a measurement target includes: a multi-sine signal generation unit that generates a multi-sine signal; a sweep sinusoidal wave generation unit that generates a plurality of sweep sinusoidal waves; an input signal switching unit that selects any one of the multi-sine signal and the sweep sinusoidal waves so as to input the selected one to the measurement target; a data acquisition unit that acquires, at a predetermined sampling frequency, sampling data of an input signal which is input to the measurement target and sampling data of an output signal which is output from the measurement target; and a characteristic calculation unit that calculates a frequency characteristic including the gain and the phase of the input and output signals in the measurement target from the sampling data of the input and output acquired.