Novel phenoxyacetic acid derivatives represented by general formula (I), and pharmacologically acceptable salts thereof, which exhibit an excellent beta 3-adrenergic receptor stimulating effect and are useful as preventive or therapeutic agents for obesity, hyperglycemia, diseases due to hyperkinesia of intestine, pollakiuria, urinary incontinence, depression, cholelithiasis or diseases due to hyperkinesia of biliary tract: wherein R is hydroxyl or the like; one of R and R is hydrogen, halogeno or the like, and the other thereof is hydrogen; and R is halogeno or the like.