It has been reported that there is a subgroup of dermatomyositis (DM) patients with rapidly progressive interstitial lung disease (ILD) who have mild muscle symptoms, slightly increased levels of muscle enzymes, and absence of anti-Jo-1 antibody. A 51-year-old woman with DM was intubated requiring mechanical ventilation because of a rapidly progressing ILD in spite of the absence of the typical poor prognostic factors. A high dose or pulse therapy of corticosteroids was not effective, but additional treatment of cyclosporine gradually improved her respiratory condition. It is not clear why a rapidly progressive ILD occurred in this case lacking poor prognostic factors. However, if corticosteroid treatment is not effective, additional administration of cyclosporine in the early period of rapidly progressive ILD may rescue deteriorating cases.