A hydrocarbon synthesis reaction apparatus synthesizes hydrocarbons by a Fischer-Tropsch synthesis reaction. The apparatus includes a reactor; a flowing line; a first cooling unit; a second cooling unit; a first separating unit which separates the liquid hydrocarbons condensed by the first cooling unit from the gaseous hydrocarbons; and a second separating unit which separates the liquid hydrocarbons condensed by the second cooling unit from the gaseous hydrocarbons. The first cooling unit cools the hydrocarbons which flow through the flowing line to a temperature range equal to or lower than a condensing point at which a wax fraction condenses, and higher than a freezing point at which the wax fraction solidifies. The second cooling unit cools the hydrocarbons which flow through the flowing line to a temperature range lower than the temperature to which the gaseous hydrocarbons are cooled by the first cooling unit, and higher than a freezing point at which a middle distillate solidifies.