Ectopic Hamartomatous thymoma(EHT) is a rare benign tumor that occurs mainly in the supraclavicular or suprasternal area. Since this entity was first reported by Smith et al. in 1982, less than 50 cases have been reported in the literature. Recognition of EHT is important and needs to be differentiated from high-grade sarcomas such as synovial sarcoma or malignant peripheral nerve sheath tumor because EHT follows a benign clinical course. We experienced a case of ectopic hamartomatous thymoma in the suprasternal area in a 53-year-old man. Here, we present the case with a review of the related literatures.