Patent ID: 8478255

Claim:
A portable terminal device comprising: an address book storing portion that stores an address book indicating names and telephone numbers or electronic mail addresses of other parties of communication; a concealed character string generating portion that generates a concealed character string in which a part or a whole of characters of the names and the telephone numbers or the electronic mail addresses of the other parties of communication is concealed, said concealed character string is generated by concealing a first character or a second character among characters of the names and the telephone numbers or the electronic mail addresses, said first character being a character other than a character frequently used and the second character being a character found as one of a predetermined character of the names and the telephone numbers or the electronic mail addresses and found as a predetermined character of any other names and telephone numbers or electronic mail addresses; and a display portion that displays, in a first display mode, a name and a telephone number or an electronic mail address of other party of communication designated by a user based on the address book without concealing characters of the name and the telephone number or the electronic mail address of the other party of communication designated by the user, and that displays, in a second display mode, the name and the telephone number or the electronic mail address of the other party of communication designated by the user as the concealed character string generated by the concealed character string generating portion.