A method, for use in a charging system including a vehicle in which a battery is installed, a charging facility, and an information terminal, for changing a charging schedule of the battery after creating the charging schedule without re-inserting a charging cable includes: receiving a request for a change of the charging schedule; acquiring, from the charging facility, a charging parameter applied in a case where the charging schedule is changed in response to the request for the change of the charging schedule as received; and creating a charging schedule after the change using the charging parameter acquired from the charging facility.