The purpose of this article was to describe the clinical and microscopic features of a foreign‐body granuloma in submental region that resulted from a fish bone embedded in the floor of mouth. A 45‐year‐old female patient complained of a hard mass in submental region. Clinical examination showed a non‐compressible, firm, fixed lump, painless on palpation. Ultrasound examination showed an internally uneven, uncircumscribed, hypoechoic mass with a steaky hyperechoic spot of 1.1 cm length in the center. A microscopic examination showed newly‐formed granuloma, composed of lympocytes and epithelioid cells, and some microabscess with neurophiles. The final diagnosis was a foreign‐body granuloma with fish bone. Even though foreign‐body granulomas in submental region are rare lesions, surgeon should be familiar with their features and include them in the differential diagnosis of tissue masses.