The present invention aims to provide a control apparatus for an internal combustion engine that can precisely determine the presence or absence of blow-by of fresh air into an exhaust path in the internal combustion engine with a supercharger. A control apparatus for an internal combustion engine according to the present invention includes: a supercharger; an intake pipe pressure obtaining unit that detects or estimates an intake pipe pressure; an intake variable valve apparatus capable of changing a valve timing of an intake valve; an exhaust variable valve apparatus capable of changing a valve timing of an exhaust valve; a storing unit that stores information about a reference intake pipe pressure that is a value that depends on the valve timing of the intake valve but does not depend on the valve timing of the exhaust valve; a reference intake pipe pressure obtaining unit that obtains the reference intake pipe pressure for the valve timing of the intake valve; and a blow-by determining unit that determines the presence or absence of blow-by of fresh air into an exhaust side based on a result of comparison between the intake pipe pressure and the reference intake pipe pressure.