The present invention provides an information registration system, a server device, a server processing program, and an information registration method which are capable of efficiently registering a telephone number without hesitation of the user and recognizing an identical person using the telephone number thus registered.According to the present invention, an information registration system is provided with a server device and a terminal device which has a browser function and is connectable to the server device through a communication means. The terminal device is provided with a display means for displaying a specified page and a determination request sending means for sending to the server device a telephone number registration determination request including a telephone number designated by a user through thus displayed page.The server device is provided with a registration list memory means for memorizing a registration list on which the telephone number is registered; a registration determination request reception means for receiving the registration determination request; a registration determination means for determining whether or not the telephone number included in the registration determination request is registered on the registration list; an approval request information sending means for sending approval request information for encouraging approval to the telephone terminal device, when a call is made to the telephone terminal device corresponding to the telephone number through a communication means and the call is answered, in a case where the telephone number is not registered on the registration list; and a registration means for registering the telephone number included in the registration determination request on the registration list, in a case where approval information indicative of the approval is received from the telephone terminal device in response to the approval request information.