An accessory middle cerebral artery (AMCA) is a variant vessel that branches from the anterior cerebral artery (ACA) and runs through the Sylvian fissure along the middle cerebral artery (MCA). We report a case of acute embolic occlusion of the AMCA that was treated with thrombectomy using direct aspiration first pass technique (ADAPT). An 88-year-old woman with a history of atrial fibrillation, loss of consciousness, and right hemiparesis was referred to our hospital. Diffusion-weighted magnetic resonance imaging (MRI) showed high signal intensity in the left frontal lobe, insular cortex, and deep white matter, and magnetic resonance angiography (MRA) demonstrated left internal carotid artery (ICA) occlusion. Mechanical thrombectomy using the ADAPT technique was performed with complete recanalization. Final angiography revealed left ACA and AMCA because of the thrombus located at the origin of the left ACA and AMCA. In the case of an acute ischemic stroke associated with AMCA, it is difficult to understand and recognize the anatomy of the vessel before thrombectomy. Therefore, the ADAPT technique, which can treat acute embolic occlusion without lesion passing, is recommended due to its safety. If there is a mismatch between the perfusion area of the occluded artery and the ischemic area or the neurological findings before thrombectomy, it is extremely important to keep in mind the presence of vessel variation in the MCA.