We report a rare case of patient with dermatomyositis (DM) who developed spontaneous pneumomediastinum (PnM) and subcutaneous emphysema. She was successfully treated with oral prednisolone and cyclosporine A (CsA). We reviewed the cases of PnM in patients with DM treated with CsA. A review of four previously reported cases revealed that treatment with systemic glucocorticoid and CsA was effective for the DM and PnM. We indicate that initial and early treatment of the patients with DM and PnM with CsA enabled rapid tapering of the dose of glucocorticoid and improved the disease.