A method for analyzing an infrared spectroscopy spectrum of a polyacrylonitrile-based fiber, the method comprising: 1) measuring an infrared spectroscopy spectrum of an inspection target to which an attenuated total reflection method is applied; characterized by 2) correcting a C=N peak height in the infrared spectroscopy spectrum through Equations 1 and 2 below using the measured spectrum: Peak height correction value = B 2 C C = A 2 − A 1 × B 2 B 1 A 0 wherein in Equations 1 and 2, A 0, A 1, A 2, B 1 and B 2 are respective measured peak height values of the infrared spectroscopy spectrum, A 0 is a C-H peak height of a nonvolatile liquid material, A 1 is a C-H peak height of a polyacrylonitrile-based fiber, A 2 is a C-H peak height of the polyacrylonitrile-based fiber infiltrated by the nonvolatile liquid material, B 1 is a C=N peak height of the polyacrylonitrile-based fiber, and B 2 is a C=N peak height of the polyacrylonitrile-based fiber infiltrated by the nonvolatile liquid material, wherein the nonvolatile liquid material is one or more selected from: paraffin oil, aliphatic ester compounds, aliphatic ether compounds, and aliphatic alcoholic compounds, wherein in step 1) above, the infrared spectroscopy spectrum is obtained for each of a total of three inspection targets by measuring with an attenuated total reflection method using an infrared spectrometer, and the inspection targets are a first inspection target sampled from a polyacrylonitrile-based fiber, a second inspection target obtained by infiltrating a nonvolatile liquid material into the first inspection target, and a third inspection target which is a nonvolatile liquid material, respectively; and wherein the infrared spectroscopy spectrum is obtained by bringing the inspection targets into contact with an attenuated total reflection crystal, irradiating the inspection targets with light, and then detecting and measuring the light reflected from the attenuated total reflection crystal. 1) measuring an infrared spectroscopy spectrum of an inspection target to which an attenuated total reflection method is applied; characterized by 2) correcting a C=N peak height in the infrared spectroscopy spectrum through Equations 1 and 2 below using the measured spectrum: Peak height correction value = B 2 C C = A 2 − A 1 × B 2 B 1 A 0 wherein in Equations 1 and 2, A 0, A 1, A 2, B 1 and B 2 are respective measured peak height values of the infrared spectroscopy spectrum, A 0 is a C-H peak height of a nonvolatile liquid material, A 1 is a C-H peak height of a polyacrylonitrile-based fiber, A 2 is a C-H peak height of the polyacrylonitrile-based fiber infiltrated by the nonvolatile liquid material, B 1 is a C=N peak height of the polyacrylonitrile-based fiber, and B 2 is a C=N peak height of the polyacrylonitrile-based fiber infiltrated by the nonvolatile liquid material, wherein the nonvolatile liquid material is one or more selected from: paraffin oil, aliphatic ester compounds, aliphatic ether compounds, and aliphatic alcoholic compounds, wherein in step 1) above, the infrared spectroscopy spectrum is obtained for each of a total of three inspection targets by measuring with an attenuated total reflection method using an infrared spectrometer, and the inspection targets are a first inspection target sampled from a polyacrylonitrile-based fiber, a second inspection target obtained by infiltrating a nonvolatile liquid material into the first inspection target, and a third inspection target which is a nonvolatile liquid material, respectively; and wherein the infrared spectroscopy spectrum is obtained by bringing the inspection targets into contact with an attenuated total reflection crystal, irradiating the inspection targets with light, and then detecting and measuring the light reflected from the attenuated total reflection crystal. A 0, A 1, A 2, B 1 and B 2 are respective measured peak height values of the infrared spectroscopy spectrum, A 0 is a C-H peak height of a nonvolatile liquid material, A 1 is a C-H peak height of a polyacrylonitrile-based fiber, A 2 is a C-H peak height of the polyacrylonitrile-based fiber infiltrated by the nonvolatile liquid material, B 1 is a C=N peak height of the polyacrylonitrile-based fiber, and B 2 is a C=N peak height of the polyacrylonitrile-based fiber infiltrated by the nonvolatile liquid material, wherein the nonvolatile liquid material is one or more selected from: paraffin oil, aliphatic ester compounds, aliphatic ether compounds, and aliphatic alcoholic compounds, wherein in step 1) above, the infrared spectroscopy spectrum is obtained for each of a total of three inspection targets by measuring with an attenuated total reflection method using an infrared spectrometer, and the inspection targets are a first inspection target sampled from a polyacrylonitrile-based fiber, a second inspection target obtained by infiltrating a nonvolatile liquid material into the first inspection target, and a third inspection target which is a nonvolatile liquid material, respectively; and wherein the infrared spectroscopy spectrum is obtained by bringing the inspection targets into contact with an attenuated total reflection crystal, irradiating the inspection targets with light, and then detecting and measuring the light reflected from the attenuated total reflection crystal.