The natural history of primary hyperparathyroidism, due to parathyroid adenoma, is unknown. Furthermore, spontaneous resolution of parathyroid necrosis or hemorrhage is rare and usually asymptomatic. Here, we report a case of parathyroid apoplexy of primary hyperparathyroidism, presenting as auditory hallucinations, accompanied with hypocalcemia. A 39-year-old man who was incidentally diagnosed with primary hyperparathyroidism, and waiting surgery for parathyroidectomy presented to psychiatric service with auditory hallucinations. He developed tetany, while taking psychiatric drugs. On a follow-up investigation, his serum calcium level fell from 11.8 to 5.8 mg/dL. His intact parathyroid hormone level also decreased from 1,017 pg/mL to 71.1 pg/mL. The parathyroid apoplexy was confirmed after a surgical removal of the infarcted adenoma. The auditory hallucinations disappeared, and serum calcium level was returned to within the normal range.