Novel substituted carboxylic acid derivatives which bind as ligands to human peroxisome proliferator activated receptor (PPAR) to activate the receptor and thereby exhibit potent effects of decreasing neutral fat, cholesterol, and blood sugar; and a processes for preparing the derivatives. Specifically, substituted carboxylic acid derivatives represented by general formula (1), and pharmaceutically acceptable salts and hydrates of the derivatives, and a processes for preparing the derivatives, the salts, or the hydrates ##STR00001##