A thermal sensitive recording medium which has a feature to change the color of recorded pattern slowly and spontaneously after development, and the recorded pattern which has several days passed can be easily distinguished from that of just after development. Said thermal sensitive recording medium contains 4-hydroxybenzoic acid ester represented by general formula (I) as a color developer and uses triphenylmethane-based leuco dye and reddish color developing leuco dye whose maximum absorption wave length is 450.about.560 nm as a dye precursor. ##STR1## In this formula, R represents unsubstituted or substituted lower alkyl group of carbon number 1-7 or benzyl group.