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.