A drowsiness estimating apparatus is provided with: an imager configured to take a face image of a driver of a vehicle; a detector configured to detect a duration of a mouth movement of the driver and whether or not the mouth movement has periodicity, on the basis of the face image; a determinator configured to determine a type of the mouth movement on the basis of the duration and whether or not the mouth movement has the periodicity; and an estimator configured to estimate drowsiness of the driver on the basis of the type of the mouth movement.