A surgical treatment device is provided with: an action portion； a light emitting part that radiates laser light onto living tissue； a light receiving part that receives scattered light of the laser light scattered by the living tissue； a light detection unit that detects the intensity of the scattered light received by the light receiving part； a frequency analysis unit that obtains time-series data indicating a temporal change in the intensity of the scattered light detected by the light detection unit, to extract an amount of frequency spectrum shift of the scattered light, included in the time-series data； and a determination unit that determines a feature of a blood vessel in the living tissue on the basis of the amount of frequency spectrum shift.
