A time information display system includes: a storage unit for storing document data; a date/time character string detecting unit for detecting whether or not a character string is contained with a character string of the document data; a relative date/time detecting unit operated in detecting a date/time expression by the date/time character string detecting unit, the relative date/time detecting unit detects whether or not a date/time character string is equal to a relative date/time expression; an absolute date/time converting unit for converting the relative date/time expression into an absolute date/time expression; a unit for storing the absolute date/time character string; a unit for calculating difference date/time between present date/time and the absolute date/time; a relative date/time converting unit for converting the calculated difference date/time into relative date/time with respect to the present date/time; and a storage unit for storing the relative date/time character string.