Lipomas are benign tumors consist of mature adipocytes, and rarely occurred in oral cavity. The etiology of lipoma remains unclear. Clinical appearance of lipoma is usually soft, yellow, asymptomatic nodular mass covered by normal mucosa. Treatment option of lipoma is mainly local excision and the recurrence is rare. We report a patient of 72-year-old female with lipoma at the floor of mouth. Intraoral examination revealed yellow, soft, painless mass at the floor of mouth with intact oral mucosa. Magnetic resonance imaging showed signal enhancement both on T1WI and T2WI images. Tumor excision was performed. Pathological diagnosis was lipoma, and consistent with clinical and imaging examination. Wound healing is good without complication. No recurrence of the lesion was noted during postoperative follow-up period.