Provided is a reliquefaction device with which a gas gasified from a liquid can be efficiently reliquefied. A plurality of flow passages include: a mixing flow passage which is connected to the downstream end section of one among a liquid flow passage and a gas flow passage and allows a fluid mixture to flow so that a reliquefaction promoting liquid flowing through the liquid flow passage and a reliquefaction target gas flowing through the gas flow passage are mixed and the reliquefaction of the reliquefaction target gas is promoted by direct heat exchange; and a gas cooling flow passage which allows a coolant to flow and cool the reliquefaction target gas by indirect heat exchange with the reliquefaction target gas through a separation wall, thereby suppressing the gasification of the reliquefaction promoting liquid when the reliquefaction target gas is mixed with the reliquefaction promoting liquid flowing through the liquid flow passage.