Soft tissue implantation of thyroid tissue is a very rare event. Needle tract implantation of thyroid carcinoma after fine-needle aspiration (FNA) biopsy has been occasionally reported, but implantation of benign thyroid tumor tissue is extremely rare. Rupture of thyroid tissues during surgery or trauma may cause the thyroid tissue to be implanted and result in multiple palpable nodules in soft tissue of the neck. Several reports have shown the possibility of implantation of normal or hyperplastic thyroid tissues in soft tissue. We herein report a case of implantation of adenomatous hyperplastic tissue in the neck along the trochar and previous operation site after endoscopic thyroid surgery, which was successfully treated by complete excision.