To provide an air-intake device capable of keeping temperature of air sucked to an engine low and preventing moisture from being contained in the air to be sent to the engine.

In the small planning boat having an engine 4 and a fuel tank 5 installed in a hull, the fuel tank 5 is arranged in front of the engine 4, an external air introduction means (an external air introducing pipe 10) is arranged in the hull, a first air-intake pipe 21 is extended from the engine 4, an air-intake port 22 of the first air-intake pipe 21 is opened at a rear part of the fuel tank 5 and a water-avoiding member 23 for preventing water from flowing in from the intake air-port 22 is arranged below the air-intake port 22.