We report a case of sialolithiasis of an accessory parotid gland in the cheek demonstrated by computed tomography and sialography. The accessory parotid gland was located anterolateral to the masseter muscle and was isolated from the main parotid gland. The calculus developed from this accessory parotid gland, and the main parotid gland was free of sialolithiasis and inflammation. To our knowledge, this is the first report concerning sialolithiasis in an accessory parotid gland. The calculus was removed without facial nerve injury or salivary fistula via a peroral approach.