We describes a patient with hypokalemia-induced rhabdomyolysis due to primary aldosteronism (PA), who suffered from slowly progressive muscle weakness after laparoscopic adrenalectomy, and was later diagnosed with coexisting sporadic inclusion body myositis (sIBM). A 54-year-old Asian male presented with severe muscle weakness of both lower extremities. Laboratory findings showed profound hypokalemia, and extreme elevation of the serum creatine phosphokinase levels, suggestive of hypokalemia-induced rhabdomyolysis. Further evaluation strongly suggested PA by an aldosterone-producing adenoma, which was successfully removed surgically. However, muscle weakness slowly progressed one year after the operation and a muscle biopsy demonstrated findings consistent with sIBM. This case is the first report of hypokalemia-induced rhabdomyolysis by PA coexistent with sIBM, to the best of our knowledge.