A predicted menstruation start date calculation apparatus includes a date information acquisition unit that acquires a number of menstrual cycle days and a number of high temperature phase days over multiple menstrual cycles of a woman, a type classification unit that performs classification into a specific type indicating that the number of menstrual cycle days is unstable and the number of high temperature phase days is stable, and into one or more types other than the specific type, and a calculation unit that calculates the predicted menstruation start date based on the classification by the type classification unit.
