To provide a control device of an internal combustion engine facilitating activation of a catalyst by increasing the amount of air supplied to the catalyst.

The internal combustion engine 10 is equipped with an exhaust gas purification catalyst 40 for purifying exhaust gas and a variable valve operating mechanism for adjusting valve characteristics of at least one of an intake valve 32 and an exhaust valve 38 of the engine 10. The control device 70 of the internal combustion engine 10 sets a valve overlap period wherein the intake valve 32 and the exhaust valve 38 open with overlap to increase intake air supplied to the exhaust gas purification catalyst 40 when the intake air flows into the combustion chamber 20 of the engine 10 in an idle operation state.