An arousal-level determining apparatus according to a present embodiment determines a subjects arousal level on the basis of a biological signal detected from a subject. The arousal-level determining apparatus measures a pulsation rate for each time interval on the basis of biological signals detected from the subject, and determines whether the subject is trying to be awake from a change in the pulsation rate, and corrects the subjects arousal level when the subject is trying to be awake.
