A method controlling a mechanical compression ratio of a cylinder by a variable compression mechanism, controlling a closing timing of an intake valve by a variable valve timing mechanism, and controlling an air flow in the cylinder by an air flow control valve in a spark ignition type internal combustion engine, the air flow control valve is a swirl control valve or a tumble control valve adapted to control the flow of air occurring inside a combustion chamber of the spark ignition type internal combustion engine and to control the amount of intake air fed to the combustion chamber to a certain extent, wherein a closing timing of the intake valve is shifted as the engine load becomes lower in a direction away from intake bottom dead center until a limit closing timing enabling control of the amount of intake air fed into a combustion chamber, wherein an extremely low load region is a region of a load lower than the engine load when said closing timing of the intake valve reaches said limit closing timing, wherein the mechanical compression ratio of the cylinder is expressed by (combustion chamber volume + stroke volume at the time of a compression stroke) /combustion chamber volume, and an expansion ratio of the cylinder is expressed by (combustion chamber volume + stroke volume of the piston at the time of an expansion stroke) /combustion chamber volume, characterized in that the expansion ratio is made a maximum expansion ratio of 20 or more by making the mechanical compression ratio maximum at the time of engine low load operation and at the time of engine low speed, and the actual compression ratio at the time of engine low load operation is made within a range of about ±10% with respect to the actual compression ratio at the time of engine medium and high load operation, by retarding the closing timing of the intake valve; and, the opening of the air flow control valve is made smaller so that a swirl ratio or tumble ratio in the cylinder becomes greater and an amount of intake air fed into the combustion chamber becomes smaller when the engine load is in the extremely low load region, than when the engine load is not in the extremely low load region. a closing timing of the intake valve is shifted as the engine load becomes lower in a direction away from intake bottom dead center until a limit closing timing enabling control of the amount of intake air fed into a combustion chamber, wherein an extremely low load region is a region of a load lower than the engine load when said closing timing of the intake valve reaches said limit closing timing, wherein the mechanical compression ratio of the cylinder is expressed by (combustion chamber volume + stroke volume at the time of a compression stroke) /combustion chamber volume, and an expansion ratio of the cylinder is expressed by (combustion chamber volume + stroke volume of the piston at the time of an expansion stroke) /combustion chamber volume, characterized in that the expansion ratio is made a maximum expansion ratio of 20 or more by making the mechanical compression ratio maximum at the time of engine low load operation and at the time of engine low speed, and the actual compression ratio at the time of engine low load operation is made within a range of about ±10% with respect to the actual compression ratio at the time of engine medium and high load operation, by retarding the closing timing of the intake valve; and, the opening of the air flow control valve is made smaller so that a swirl ratio or tumble ratio in the cylinder becomes greater and an amount of intake air fed into the combustion chamber becomes smaller when the engine load is in the extremely low load region, than when the engine load is not in the extremely low load region.