Provided is a motion detection system capable of alleviating a burden on a caregiver which could arise when a plurality of types of notification target motions is detected during a short time period. A motion detection system (300) includes: an acquisition unit (52) for acquiring motion data indicating a motion of a person a detection unit (150) for detecting a predetermined motion of the person using the motion data a selection unit (160) for, when a plurality of types of output candidate motions is detected by the detection unit (150) during a predetermined time period, selecting an output target motion from among the output candidate motions such that types of the output candidate motions are made fewer than the plurality of types and an output unit (170) for outputting the output target motion selected by the selection unit (160).