To detect biological information with high sensitivity and efficiency in a short processing time without requiring a high-speed CPU or large memory.SOLUTION: There is provided a vital sensor that transmits a modulated wave based on frequency sweep and receives the reflected wave, mixes the transmitted wave and the received wave, and outputs a beat signal having a frequency difference between the two waves. The vital sensor extracts the difference signal by subtraction (difference circuit 27) between the beat signals in the sweep before and after the sweep repeated continuously, calculates an integrated power value obtained by integrating the power of this difference signal for each sweep (power integrating circuit 28), and determines information on minute fluctuations, respiratory rate, heart rate, etc. in the living body by detecting changes in the integrated power value for each sweep (measurement circuit 29).SELECTED DRAWING: Figure 1【課題】高速のＣＰＵや大きなメモリも必要とすることなく、短い処理時間で効率よく、かつ高い感度にて、生体の情報を検知する。【解決手段】周波数掃引に基づき変調波を送信すると共にその反射波を受信し、送信波と受信波をミキシングして両波の差の周波数を持つビート信号を出力するバイタルセンサにおいて、連続して繰り返される掃引の前後の掃引におけるビート信号間の減算（差分回路２７）により差分信号を抽出し、この差分信号のパワーを積算した積算パワー値を掃引毎に演算し（パワー積算回路２８）、この掃引毎の積算パワー値の変化を検出することにより、生体の微小変動の情報、呼吸数、心拍数等を判定する（計測回路２９）。【選択図】図１
