To provide a cooling device for cooling liquid fuel to be supplied to an engine for a ship, configured to reduce noise and vibration, while enabling easy maintenance and efficient cooling.

A fuel cooler 10 has a fuel passage 20, air-cooled parts 23, Peltier elements 22, and heat transfer members 21. Second liquid fuel to be supplied to a diesel engine flows in the fuel passage 20. The air-cooled part 23 is arranged outside the fuel passage 20, and discharges heat to surrounding air. The Peltier element 22 is arranged on an outer wall surface of the fuel passage 20, and moves the heat of the fuel passage 20 to the air-cooled part 23. The heat transfer member 21 is arranged in the fuel passage 20, and is connected to a wall surface provided with the Peltier element 22.