PURPOSE: To prevent character attributes added to a character string to be replaced from being lost by character string replacement by providing a means for adding the character attributes of the character string to be replaced to a replacing character string when the character attributes are added to the character string to be replaced.

CONSTITUTION: Whether or not the character attributes are added to the character string to be replaced is judged in a processing 11 first and the character string replacement of the processing 13 is conducted when the character attributes are not added. On the other hand, when the character attributes are added to the character string to be replaced, the common character attributes added to the entire character string to be replaced are added to the replacing character string in the processing 12. For instance, the character emphasis of an underline in common to the three characters of the character string 21 to be replaced is added to all the characters of the replacing character string 22 and the replacing character string 23 for which the character emphasis of the underline is added to all the characters is defined as the replacing character string. Finally, the character string replacement of the processing 13 is conducted and the character string 21 to be replaced and the replacing character 23 are replaced. Thus, the character attributes added by a user can not be lost by the character string replacement.