Abstract: The author reports a case of the hyperfunction of an ectopic parathyroidoma in the anterior superior mediastinum. A 58-year-old woman with pain in the right hip was diagnosed with multiple bone metastases through magnetic resonance imaging (MRI). Computed imaging revealed a soft tissue mass shadow in the anterior superior mediastinum of the patient's tomography (CT) chest. Super-bone imaging through whole-body bone scintigraphy and parathyroid scintigraphy indicated that the mass was an anectopic mediastinum parathyroidoma. Through pathological diagnosis after thoracoscopic surgery, the mass was identified as a parathyroid adenoma with hyperfunction. The ectopic parathyroid adenoma of the anterior superior mediastinum with hyperfunction and accompanied by changes in super-bone imaging is clinically rare. Technetium methylene diphosphonate (⁹⁹Tc^m-MDP) whole-body bone scintigraphy combined with technetium sestamibi (⁹⁹Tc^m-MIBI) parathyroid scintigraphy can provide important information for the diagnosis of suspected ectopic parathyroidoma.