An intake system of an engine includes an engine and an intake manifold. The intake manifold defines individual intake air passageways each connecting one of cylinders to a volume chamber. Each of the individual intake passageways includes a first route and a second route. The first route has a natural frequency, of an air column, synchronized with a first revolution higher than an engine revolution for maximum torque such that a dynamic supercharging effect is obtained at the first revolution. The second route has a natural frequency, of an air column, synchronized with a second revolution higher than the engine revolution for maximum torque such that a dynamic supercharging effect is obtained at the second revolution. The second revolution differs from the first revolution. A difference between the first and second revolutions is set lower than or equal to 15% of a maximum engine revolution.