A 61-year-old woman presented with loss of consciousness. Echocardiography revealed a hypoechoic, round mass of 12×13 mm with a smooth border in the left ventricular outflow tract, leading to a diagnosis of loss of consciousness caused by left ventricular outflow tract obstruction, and surgical excision of the mass was performed. The mass, with a smooth, elastic soft surface and filled with yellow, creamy contents, was observed within a range from the subannular region of the left coronary cusp to the anterior mitral leaflet. Pathological examination showed central degeneration and liquefaction, as well as cystic, coarse-granular calcium deposition surrounded by inflammatory cell infiltration and fibroblast proliferation. No tumor cells were seen. Abscess was excluded by preoperative clinical presentations, hematologic data, and culture testing, and thus the mass was considered as caseous calcification of the mitral annulus. Here, we report a case of caseous calcification of the mitral annulus, a rare nonneoplastic lesion thought to be a variant of mitral annular calcification, with literature review.