A method for producing butadiene comprises a step of obtaining a product gas containing butadiene, by feeding a raw-material gas containing straight-chain butene and an oxygen-containing gas containing molecular oxygen to a reactor and performing oxidative dehydrogenation reaction in the presence of a catalyst, wherein the catalyst comprises a composite oxide containing molybdenum and bismuth, and the concentration of hydrocarbons having 5 or more carbon atoms in the raw-material gas is 0.05 mol % to 7.0 mol %.