A butadiene production system and a butadiene production method are provided in which the yield is high and environmental load can be reduced. The butadiene production system (1) includes: a gas preparation device (10) that heats raw materials to prepare a mixed gas including hydrogen and carbon monoxide; an ethanol production device (12) that is provided downstream of the gas preparation device (10) and brings the mixed gas into contact with a first catalyst to obtain ethanol; a butadiene production device (16) that is provided downstream of the ethanol production device (12) and brings the ethanol into contact with a second catalyst to obtain butadiene; and return means (18) for returning hydrogen, ethylene, and the like, which are produced as by-products in the butadiene production device (16), to the gas preparation device (10). In addition, in the butadiene production method, the butadiene production system (1) is used.