In a combustion unit, a fuel collision member is disposed between a fuel injection valve and a combustion chamber. The fuel collision member is positioned so that, a part of fuel injected from said fuel injection valve is introduced into the combustion chamber while colliding with the fuel collision member, and the other part of fuel is directly introduced into the combustion chamber without colliding with the fuel collision member. Thus, fuel introduced into the combustion chamber is atomized while being introduced into the combustion chamber in a wide range.