To provide an external character display system, method and program capable of replacing an external character with an external character image data, and displaying the same.

A Web browser data transmitting and receiving means 21 receives the HTML data transmission demand from an input and output device 1. The external character retrieving means 22 takes out the HTML data from a Web browser display data storing part 31, and retrieves the presence or absence of the external character. In a case of the presence of the external character, an external character image data replacement means 23 replaces a character code of the external character into the tag information composed of an name of an external character image data file and an external character image data display size. The Web browser data transmitting and receiving means 21 transmits the HTML data after the replacement, to the input and output device 1, and the input and output device 1 displays the received HTML data by the Web browser.