To provide a control device for an internal combustion engine capable of keeping suitable completion frequency of deterioration determination of exhaust emission control catalyst while improving fuel economy at a time of light load operation by variable control of at least one of maximum lift and operating angle of an intake valve.

An electronic control device 41 detects a quantity of a state relating to degree of purification of exhaust gas of a catalytic converter 19 and performs deterioration determination of the catalytic converter 19 based on change of the quantity of the state during a period until accumulated intake air quantity exceeds a fixed value, and variably controls at least one of the maximum lift and operating angle of the intake valve 21. The electronic control device 41 increases at least one of the maximum lift and operating angle of the intake valve 21 at a time of deterioration determination of the catalytic converter 19 as compared with that at a time of not deterioration determination.