The liquid fuel synthesizing apparatus (1) for efficient synthesis of liquid fuel from biomass, such as plant for a raw material, comprised of reactors (2) with a catalyst incorporated therein, coolers (3) for cooling of synthesized gaseous matter and extracting of liquid fuel, and temperature adjustment means (7) for regulating by heat exchange any unreacted gas after recovery of liquid fuel to reaction temperature suitable for liquid fuel gas synthesis, wherein the reactors, the coolers and the temperature adjustment means are arranged multistage inline-straightly along gas flow. The temperature adjustment means (7) and the reactors (2) are disposed in the constant temperature room (8) in parallel. The coolers (3) are disposed apart from the constant temperature rooms (8).