Abstract: A portable information terminal such as mobile communication terminal having an earphone jack for sound input/output, PHS (personal handy-phone system), PDA (personal digital assistants), and mobile personal computer; a digital camera to connect to the portable information terminal, a digital camera connected portable terminal device comprising the portable information terminal and the digital camera, as well as to a method of controlling such a portable information terminal. The existing earphone jack provided on portable information terminals can be adopted as the plug for the digital camera or insertion plug for the connector of USB cable, so that the cost can be lowered and the system made compact to provide a highly flexible portable information terminal and a digital camera for use with the portable information terminal.