Histopathologically adult extracardiac rhabdomyoma is a benign tumour of mature striated muscle. It is a slow- growing tumour with predilection to occur in head and neck region. They appear mainly as a solitary lesion, and about 15% of them can be multicentric. A 56-year-old man presented to us with the floor of mouth swelling persisted for one year and the right neck swelling for three years mimicking a plunging ranula. Radiological imaging revealed enhancing mass at the floor of mouth and submandibular region. The mass represented a nonvascular benign tumour. Subsequently, the patient underwent excision of the mass via transcervical and transoral method. Histopathological examination revealed adult type of extracardiac rhabdomyoma. Adult type of extracardiac rhabdomyoma should be considered in the differential diagnosis for the head and neck masses. A complete excision will reduce the risk of recurrence.