1. A gait change determination device comprising: a main body arranged to be worn by a user in a predetermined area; an accelerometer that detects an acceleration of the main body; and a control unit that is arranged and programmed to determine a change in a gait of the user; wherein the control unit includes: a specification unit that is arranged and programmed to, based on the acceleration detected by the accelerometer, specify a trajectory of the predetermined area on which the main body is worn during walking; a first calculation unit that is arranged and programmed to calculate a temporal change in the trajectory specified by the specification unit; and a determination unit that is arranged and programmed to, based on the temporal change calculated by the first calculation unit, determine a degree of change that is the degree of the temporal change.