A movement assist device (1) includes: a motor (4) including a stator (2) and a rotator (3)； two arm members (5, 6) connected to each of the stator and the rotator and configured to be connected to a predetermined part of a body of an equipped person (M)； a signal accepting unit (53) configured to accept a trigger signal that triggers a driving of the motor； and a driving control unit (61) configured to drive the motor so that the two arm members expand in response to a trigger that the signal accepting unit accepts a first one of the trigger signal.
