PURPOSE: To achieve uniform distribution of fuel density and to reduce unbalance of air-fuel ratio by splitting even number (more than four) of cylinders into two while arranging a fuel injection valve and an atomizer in parallel in the upstream of collected intake manifolds in respective cylinder group.

CONSTITUTION: First and second intake manifolds 2, 3 coupled respectively with first cylinder group of first and second cylinders and second cylinder group of third and fourth cylinders are provided to an internal-combustion engine comprising 4-cylinders. First and second fuel supply bodies 4, 5 are coupled to respective collecting section 2a, 3a while an atomizer 15 having a hollow tubular rolling chip and a fuel injection valve 16 are arranged closely to pass the fuel through a lateral hole in the wall face at the rolling chip side. Consequently, the fuel injected through the fuel injection valve 16 is atomized instantaneously by the atomizer 15 then passed through an intake manifold having proper length to the combustion chamber resulting in uniform distribution of fuel density.