A sleep stage determination apparatus is provided with: a first normalization unit that performs a first normalization processing on the intensity of a user's heartbeat signal calculated using a gain value of gain control that is performed on the heartbeat signal so that the peak value is controlled to be constant； a second normalization unit that performs a second normalization processing on the intensity of the heartbeat signal； a third normalization unit that performs a third normalization processing on a first normalized heartbeat intensity； and a sleep stage determination unit that determines the stage of sleep on the basis of the second normalized heartbeat intensity obtained by the second normalization unit and variances indicating data variations in a predetermined period calculated for the normalized heartbeat intensity data obtained by the first normalization unit and the third normalization unit.
