We report a case of carcinoma ex pleomorphic adenoma of a sublingual gland in a 70-year-old man. Under a clinical diagnosis of benign salivary gland tumor, excision of the mass with the sublingual salivary gland in an en bloc fashion via an intraoral approach was performed. Histopathologically, there was a rupture of the fibrous capsule and diffuse cell-rich sheets composed of myoepithelial cells with round nuclei were also seen. Immunohistochemically, the cells that composed of cell rich sheets were positive to smooth muscle actin. Final diagnosis of myoepithelial carcinoma ex pleomorphic adenoma was made.