Lipoma is a common benign tumor derived from stroma that can arise in any location where fat is normally present. Giant lipoma is defined as a lesion that is >10 cm in length and weighs >1000 g. Axillary region might have been exposed to microtraumas with each movement of upper extremity, leading to the development of giant lipoma. In this report, a 56-year-old man visited us because of a soft tissue mass on the left axilla that had been noticed 5 years before. We removed the tumor from the patient under general anesthesia. A lipoma measuring 21 cm × 12 cm in size was removed, and the weight of the mass was 455 g. The case of our patient is very interesting because there have been few reported patients with a diagnosis of a giant lipoma in a sublatissimusdorsi muscle.