Novel genetic and epigenetic factors involved in the development and prognosis of idiopathic pulmonary fibrosis (IPF) have been identified. We previously observed that erythrocyte membrane protein band 4.1-like 3 (EPB41L3) increased in the lung fibroblasts of IPF patients. Thus, we investigated the role ofEPB41L3in IPF by comparing the EPB41L3 mRNA and protein expression of lung fibroblast between patients with IPF and controls. We also investigated the regulation of epithelial–mesenchymal transition (EMT) in an epithelial cell line (A549) and fibroblast-to-myofibroblast transition (FMT) in a fibroblast cell line (MRC5) by overexpressing and silencingEPB41L3. EPB41L3 mRNA and protein levels, as measured using RT-PCR, real-time PCR, and Western blot, were significantly higher in fibroblasts derived from 14 IPF patients than in those from 10 controls. The mRNA and protein expression of EPB41L3 was upregulated during transforming growth factor-β-induced EMT and FMT. Overexpression of EPB41L3 in A549 cells using lenti-EPB41L3transfection suppressed the mRNA and protein expression ofN-cadherinandCOL1A1.Treatment with EPB41L3 siRNA upregulated the mRNA and protein expression ofN-cadherin. Overexpression ofEPB41L3in MRC5 cells using lenti-EPB41L3transfection suppressed the mRNA and protein expression offibronectinandα-SMA.Finally, treatment withEPB41L3siRNA upregulated the mRNA and protein expression ofFN1, COL1A1,andVIM.In conclusion, these data strongly support an inhibitory effect ofEPB41L3on the process of fibrosis and suggest the therapeutic potential of EPB41L3 as an anti-fibrotic mediator.