Novel tripeptide compounds having excellent HIV protease inhibitory activites and represented by general formula (I), pharmacologically acceptable salts thereof, and anti-AIDS drugs containing the same as the active ingredient. An example of the compounds is (R)-N-(2-methylbenzyl)-3-{(2S, 3S)-3-[N-(2-chromonecarbonyl)-L-asparaginyl]amino-2-hydroxy-4-phenylbutanoyl}-5, 5-dimethyl-1, 3-thiazolidine-4-carboxamide.