A congenital cholesteatoma is a benign mass formed from the keratinizing stratified squamousepithelium. It usually occurs in young children’s anterosuperior part of the middle ear. A congenitalcholesteatoma which originates from mastoid temporal bone or expands to posteriorcranial fossa is rare. Standard treatment of an intracranial cholesteatoma is surgical removalwith craniotomy. A 69-year-old woman was diagnosed with a congenital cholesteatoma of mastoidtemporal bone that expanded to the posterior cranial fossa, which was successfully treatedwith transmastoid marsupialization without craniotomy. This is a first documented case ofa congenital cholesteatoma of mastoid temporal bone that expanded to posterior cranial fossa, which was successfully treated with transmastoid marsupialization without craniotomy.