The circulation time measuring apparatus includes a signal acquisition unit that acquires an airflow signal indicating a temporal change in respiratory airflow and an oxygen saturation signal indicating a temporal change in oxygen saturation, a signal acquisition unit that acquires a predetermined first time in the airflow signal, And a second time in the oxygen saturation signal indicating an increase in the oxygen saturation corresponding to resumption of respiration at the first time based on the blood oxygen circulation time measured by the circulation time calculation unit .循環時間測定装置は、呼吸の気流の時間変化を示す気流信号、及び、酸素飽和度の時間変化を示す酸素飽和度信号を取得する信号取得部と、前記気流信号における所定の第一時刻と、前記第一時刻での呼吸再開に対応した酸素飽和度の上昇を示す前記酸素飽和度信号における第二時刻との時間差に基づいて血液の酸素運搬循環時間を測定する循環時間算出部と、を有する。
