To strengthen a vortex of gas in a combustion chamber further while avoiding the collision of spray of fuel from a fuel injection valve with the downstream end of a partition wall.

A vortex generating device consists of a partition wall 12 for demarcating the inside of an intake passage 3 in an engine into a vortex passage 14 situated in a part near the center of a combustion chamber 4 and a main passage 15 situated in a part separated from the center of the combustion chamber 4, and an air flow control valve 13 for carrying out opening/closing operation so as to block and open the main passage 15. Air is sucked into the combustion chamber 4 through the vortex passage 14 by blocking the main passage 15 with the air flow control valve 13 so that the vortex of gas is produced in the combustion chamber 4. The downstream end of the partition wall 12 is extended to the downstream side up to an extension line in an injecting direction of fuel from the fuel injection valve 2 of the engine. A notch 18 is formed in a part overlapping with the spray of fuel sprayed from the fuel injection valve 2 at the downstream end of the partition wall 12.