Novel 2-methylpropionic acid derivatives represented by general formula (I) and pharmacologically acceptable salts thereof which have an excellent beta 3 adrenaline receptor stimulating effect and are useful as preventives or remedies for obesity, hyperglycemia, diseases caused by accelerated intestinal motion, frequent urination, urinary incontinence, depression, cholelithiasis or diseases caused by accelerated biliary motion. In said Formula (I) R represents hydrogen, lower alkyl or aralkyl; R represents hydrogen, lower alkyl or halogeno; A represents oxygen or imino; the carbon atom to which (R) is attached stands for one with the R-configuration; and the carbon atom to which (S) is attached stands for one with the S-configuration.