An image data transmitting/receiving system for displaying an image having an optimum size in accordance with the resolution of an information display screen (11) of a mobile terminal (1), comprising the mobile terminal (1) and a server (7). The mobile terminal (1) comprises terminal-side symbol image data storing means (KC2) for storing data of symbol image used for producing a displayed image; and symbol image data transmission request information transmitting means (KC10B) for transmitting information related to the resolution of the information display screen (11) to the server (7). The server (7) comprises server-side symbol image data storing means (SC2A) for storing a plurality of symbol image data in accordance with the resolution of the information display screen (11); terminal resolution determining means (SC3) for determining, based on the received resolution related information, the symbol image data to be transmitted to the mobile terminal (1); and symbol image data transmitting means (SC5B) for transmitting the symbol image data in accordance with the aforementioned resolution.