An image forming apparatus connected to plural authentication servers, the image forming apparatus comprising: an acquiring unit configured to acquire user identifying information identifying a user and a password; characterized in a selecting unit configured to select server identifying information identifying two or more of the plural authentication servers for causing to perform an authentication process, from server identifying information identifying respective authentication servers of the plural authentication servers, wherein the server identifying information is selected by the user; a setting unit configured to set one or more required authentication servers as set by an administrator; an authentication process unit configured to transmit common information to the two or more authentication servers identified by unique information successively from one authentication server to another, and acquire an authentication result from the two or more authentication servers, the authentication process unit configured, when one or more required authentication servers are selected,to determine that authentication is successful upon reception of the authentication result indicating successful authentication by all the required authentication servers, the authentication process unit configured, when a required authentication server is not selected, to determine that authentication is successful upon reception of the authentication result indicating successful authentication by at least one of the two or more authentication servers; and a process unit configured to process image data upon determination of successful authentication by the authentication process unit, wherein the common information includes the user identifying information and the password, and the unique information includes the selected server identifying information. an acquiring unit configured to acquire user identifying information identifying a user and a password; characterized in a selecting unit configured to select server identifying information identifying two or more of the plural authentication servers for causing to perform an authentication process, from server identifying information identifying respective authentication servers of the plural authentication servers, wherein the server identifying information is selected by the user; a setting unit configured to set one or more required authentication servers as set by an administrator; an authentication process unit configured to transmit common information to the two or more authentication servers identified by unique information successively from one authentication server to another, and acquire an authentication result from the two or more authentication servers, the authentication process unit configured, when one or more required authentication servers are selected,to determine that authentication is successful upon reception of the authentication result indicating successful authentication by all the required authentication servers, the authentication process unit configured, when a required authentication server is not selected, to determine that authentication is successful upon reception of the authentication result indicating successful authentication by at least one of the two or more authentication servers; and a process unit configured to process image data upon determination of successful authentication by the authentication process unit, wherein the common information includes the user identifying information and the password, and the unique information includes the selected server identifying information.