To allow a user to transmit position information of a designated place using an information terminal.

A PC 3 or a portable telephone 4 as the information terminal creates and transmits an electronic mail containing information on the designated place of the user in response to an operation of the user. A mail relay center 5 acquires the electronic mail transmitted from the PC 3 or the portable telephone 4, retrieves the position of the designated place of the user on the basis of the electronic mail, and newly creates an electronic mail containing the retrieved position information to transmit it to the navigation device 1. The navigation device 1 receives the electronic mail transmitted from the mail relay center 5 via a communication terminal 2, and specifies the position of the designated place of the user on the basis of the position information included in the electronic mail.