A method of manufacturing a semiconductor device comprising: obtaining a raw light signal by selecting a predetermined wavelength band of light reflected from a wafer on which a plurality of patterns are formed; converting the raw light signal into a frequency domain; obtaining a first detection signal having a first frequency band from the raw light signal converted into the frequency domain; obtaining a second detection signal having a second frequency band from the raw light signal converted into the frequency domain, the second frequency band being different from the first frequency band; obtaining a representative value using the first detection signal, the representative value representing a profile of the plurality of patterns; and obtaining a distribution value using the second detection signal, the distribution value representing a profile of the plurality of patterns using the second detection signal. The method may include determining whether the representative value and the distribution value are within predetermined ranges respectively; and performing a following step of manufacturing the semiconductor device when the representative value and the distribution value are within respective predetermined ranges.