To improve accuracy in misfire determination, a control apparatus for an internal combustion engine that controls an internal combustion engine having a variable compression ratio mechanism capable of changing the compression ratio of the internal combustion engine includes a controller configured to: determine that a misfire occurs if the magnitude of rotational fluctuation of the internal combustion engine is equal to or larger than a misfire criterion value and to make the misfire criterion value larger during the time in which changing of the compression ratio of the internal combustion engine is in progress than during the time in which the compression ratio is not being changed.