We report a case of trigonal cavernous malformation (CM) radiologically mimicking meningioma. The computed tomographic (CT) head angiography and magnetic resonance imaging (MRI) showed a partially calcified lesion with slight contrast enhancement located in the area of the left atrium of lateral ventricle. The lesion was completely removed using microsurgery with a parieto-occipital transcortical approach. The resected mass was histologically confirmed as CM. CM should be considered as differential diagnosis in case of the atrial mass lesion due to lack of hemosiderin ring characteristically seen other seated CM.