The hydrocarbon production apparatus is provided with a gas-liquid separator for cooling gaseous state hydrocarbons drawn out from a gas phase portion of a reactor for the Fischer-Tropsch synthesis reaction and liquefying a portion of the hydrocarbons. A light liquid hydrocarbon supply line for supplying light hydrocarbons is disposed between a downstream side line which is downstream from the last stage of a gas-liquid separating unit of the gas-liquid separator, and an upstream side line which is upstream from the last stage of the gas-liquid separating unit of the gas-liquid separator, wherein the downstream side line is a liquid hydrocarbon line on the downstream side through which the light hydrocarbons having cloud points lower than the temperature at an outlet of a cooler in the last stage of the gas-liquid separating unit are flowed.