An engine control device controls control amounts of a variable valve mechanism and a spark plug, the control amounts in a homogeneous lean operation region set in a first load region are different from that in a non-lean operation region which is a stoichiometric or rich operation region set in a second load region higher than the first load region. The control device performs control, in other operation region set in a third load region between the first and second load region, so that an air-fuel ratio of the internal combustion engine is equal to that of non-lean operation region, the control amount of the variable valve mechanism is equal to that of homogeneous lean operation region and the control amount of the spark plug is equal to that of the non-lean operation region in accordance with an operation amount of an accelerator pedal.