Provided are a misfire detection apparatus and a misfire detection method for an internal combustion engine, which are capable of correctly detecting a misfire state of an engine for a vehicle small in number of cylinders and in rotational inertia without limiting control to O2 feedback control. When an air/fuel ratio of an exhaust gas exhausted from a cylinder that is a misfire determination subject is in a lean state, and when lean control is not being carried out on the internal combustion engine, enrichment processing for the air/fuel ratio is carried out. When the air/fuel ratio remains in the lean state even though the enrichment processing is carried out, it is determined that misfire occurs in the cylinder that is a misfire determination subject.