Primary aldosteronism is characterized by hypokalemic metabolic alkalosis, low plasma renin activity, elevated plasma aldosterone level and can be suspected in the patients with hypertension and unexplained hypokalemia. Small adrenal cortical adenomas are responsible for this syndrome in most cases. The incidence of thyrotoxic periodic paralysis ranges from 1.9 to 6.2 % in Japan. Thyrotoxic periodic paralysis usually subsides following treatment of hyperthyroidism and has good prognosis. A 56 year-old man presented with hyperthyroidism, hypertension and recurrent hypokalemia. During the treatment of hyperthyroidism, he repeatedly experienced weakness of both lower extremities. Hormonal evaluation was performed and he was found to have a 2*2*1.5 cm sized right adrenal tumor by abdominal computerized topography(CT). After right adrenalectomy, hypokalemic periodic paralysis was improved. Both thyroid and adrenal function should be comprehensively investigated in periodic paralysis. In conclusion, physicians must be aware of the possibility of primary aldosteronism in hyperthyroid patients with hypokalemic periodic paralysis. We report a case of aldosteronoma complicated with hyperthyroidism and literatures are reviewed.