To provide a small-sized boat wherein a sufficient supercharging effect can be achieved. An engine having an exhaust manifold is disposed such that a crankshaft thereof extends in forward and rearward directions of a boat body, and an exhaust gas turbo charger which is driven to rotate by exhaust gas from the exhaust manifold is provided rearwardly of and adjacent to the exhaust manifold and rearwardly of and adjacent to the engine. The exhaust gas turbo charger is disposed such that a shaft which connects a turbine and a compressor is directed in leftward and rightward directions of the boat body, and the turbine is disposed adjacent to the exhaust manifold and the compressor is disposed adjacent to an intake port of the engine. An inter cooler is provided sidewardly of the compressor and disposed below an intake chamber.