A 59-year-old Japanese man diagnosed with interstitial lung disease associated with amyopathic dermatomyositis with anti-melanoma differentiation-associated gene 5 (MDA-5) antibodies was treated with intravenous methyl prednisolone (PSL) 1000 mg, oral PSL 1 mg/kg, and oral cyclosporin 200 mg daily. His respiratory condition worsened after treatment with two times of intravenous cyclophosphamide and another steroid pulse therapy as well as PSL and cyclosporin. Addition of mycophenolate mofetil (MMF), 1.5 g daily improved PaO2/FiO2 (PF) ratio of the patient from 294 to 360 at 4 weeks and 416 at 15 weeks after addition of MMF. We measured cytokine concentration in preserved serum taken at 11 and 7 weeks before addition of MMF and at 4, 11, and 15 weeks after MMF administration. Of the 28 cytokines evaluated, the concentrations of fibroblast growth factors-2 (FGF-2), chemokine (C-X3-C motif) ligand 1 (CX3CL1), interleukin (IL)-1ra, IL-17A, inducible protein 10 (IP-10), and monocyte chemotactic protein-1 (MCP-1) decreased after addition of MMF. These results suggest that MMF may be beneficial to patients with interstitial lung disease by modification of the cytokine/growth factor protein expression.