A control device that changes control content of control means mounted in a vehicle, characterized by: a user information acquiring means for acquiring information on a user who owns the vehicle in which the control content should be updated, wherein the user is an individual user or a corporate user; a schedule acquisition means for acquiring a schedule relating to the vehicle, wherein the schedule acquisition means is adapted to acquire a schedule of the user who owns the vehicle on the basis of the user information output from the user information acquiring means, wherein the schedule acquisition means 23 acquires the schedule of the user from a schedule database in which an individual schedule of the user who owns the vehicle is stored or a company database in which a schedule of a corporate user in form of a company that owns company cars and commercial cars is stored on the basis of the user information; a time estimation means for estimating a time when the vehicle is not in use on the basis of the schedule acquired by the schedule acquisition means and for outputting time information indicating the estimated time; a reprogramming schedule generation means for generating and outputting change date and time when the control content should be changed, according to the estimated time output by the time estimation means; wherein the time estimation means (a) in case of an individual user is adapted to estimate a time when the vehicle is not in use on the basis of the schedule by determining whether there is a plan of the user in a programming candidate time for changing control content, and, if there is a plan of the user in the reprogramming candidate time, then determining whether the plan of the user is a plan in which the user will not use the vehicle, and (b) in case of a corporate user is adapted to estimate a time on the basis of a storage site of the schedule when the vehicle is parked at a location which cannot be reached by electric waves; and the reprogramming schedule generation means (a) in case of an individual user generates a time indicated by the time information received from the time estimating unit as the change date and time when the control content should be changed, and (b) in case of a corporate user generates a change date and time according to which changing of the control content of plural vehicles owned by the corporate user can be intensively performed in a short time. a user information acquiring means for acquiring information on a user who owns the vehicle in which the control content should be updated, wherein the user is an individual user or a corporate user; a schedule acquisition means for acquiring a schedule relating to the vehicle, wherein the schedule acquisition means is adapted to acquire a schedule of the user who owns the vehicle on the basis of the user information output from the user information acquiring means, wherein the schedule acquisition means 23 acquires the schedule of the user from a schedule database in which an individual schedule of the user who owns the vehicle is stored or a company database in which a schedule of a corporate user in form of a company that owns company cars and commercial cars is stored on the basis of the user information; a time estimation means for estimating a time when the vehicle is not in use on the basis of the schedule acquired by the schedule acquisition means and for outputting time information indicating the estimated time; a reprogramming schedule generation means for generating and outputting change date and time when the control content should be changed, according to the estimated time output by the time estimation means; wherein the time estimation means (a) in case of an individual user is adapted to estimate a time when the vehicle is not in use on the basis of the schedule by determining whether there is a plan of the user in a programming candidate time for changing control content, and, if there is a plan of the user in the reprogramming candidate time, then determining whether the plan of the user is a plan in which the user will not use the vehicle, and (b) in case of a corporate user is adapted to estimate a time on the basis of a storage site of the schedule when the vehicle is parked at a location which cannot be reached by electric waves; and the reprogramming schedule generation means (a) in case of an individual user generates a time indicated by the time information received from the time estimating unit as the change date and time when the control content should be changed, and (b) in case of a corporate user generates a change date and time according to which changing of the control content of plural vehicles owned by the corporate user can be intensively performed in a short time.