A gait change determination device includes a main body unit, an accelerometer that detects an acceleration of the main body unit, and a control unit, and determines a change in the gait of a user that wears the main body unit on a predetermined area. The control unit specifies a trajectory of a predetermined area on which the main body unit is worn during walking based on accelerations detected by the accelerometer, calculates the temporal change amount of the specified trajectory, and determines the degree of change, which is the degree of the temporal change, based on the calculated temporal change. The degree of change in the gait can be more accurately determined.