In a method of automatically changing a client program in a client/server system, when an access request is transmitted from a client program to a server program and an error occurs, the cause of the error is analyzed and when the error is caused by change of an interface of the server program, a change location of the interface of the server program is detected. A change portion and a changing scheme of the client program related to the change of the interface are decided to change the client program and the client program being currently operated is replaced by the changed client program.