To realize stable self-ignition operation in a four-cycle internal combustion engine.

This four-cycle internal combustion engine can perform a compression self-ignition operation in at least a partial operating range. In the internal combustion engine 10, an ECU 100 controls an air intake valve 33 and an exhaust valve 34 to set a first exhaust valve opening period EX1 finished before the dead center in intake air, an air intake valve opening period IN started after the dead center in intake air, and a second exhaust valve opening period EX2 for a predetermined period just before the air intake valve opening period IN. As a result, the compression end temperature of fuel/air mixture is raised by internal EGR, main flow is formed in a combustion chamber in the intake stroke, and mixing of the fuel/air mixture is improved. Therefore, pre-ignition and misfire are suppressed, and the stable self-ignition operation is allowed.