The present invention provides: 4-methyl-2-[4-(2-methylpropoxy)-3-(1H-1,2,3,4-tetrazole-1-yl)phenyl]-1,3thiazole-5-carboxylic acid and a sodium salt thereof that are useful as a therapeutic agent or a prophylactic agent for gout, hyperuricemia, and the like; crystals thereof; and a production method therefor.本發明係提供有用於作為痛風、高尿酸血症等之治療藥或預防藥的4-甲基-2-[4-(2-甲基丙氧基)-3-(1H-1,2,3,4-四唑-1-基)苯基]-1,3-噻唑-5-羧酸及其鈉鹽、以及該等之結晶、以及製造方法。