Purpose/Aim: Idiopathic pulmonary fibrosis (IPF) is the most common idiopathic interstitial pneumonia. Multiple genetic factors, environmental exposures, micro-aspirations secondary to gastroesophageal reflux, age, sex, smoking habit, and infections contribute to its etiology; consequently, its pathogenesis remains unclear. The homeostasis of gut microbiota, including bacteria, archaea, and fungi, can influence the functions of both the intestine and remote organs. There are still many unknowns regarding the effects and mechanisms of gut microbiota dysbiosis on the development of IPF. In this study, we aimed to characterize the gut microbiota of patients with IPF compared with that of healthy controls. Furthermore, we assessed the effects of antifibrotic drugs on gut dysbiosis. Materials and Methods: This study involved 12 patients with IPF receiving antifibrotic drug therapy, 12 patients with IPF not receiving antifibrotic drug therapy, and 8 healthy controls. The clinical parameters of the patients were recorded, and DNA extracted from stool samples was subjected to 16S ribosomal RNA gene sequencing of the V1–V9 hypervariable regions. Results: Campylobacterota species were detected in the patient groups but not in the control group. Staphylococcales and Gemellaceae species were not detected in the IPF groups; however, a significant relationship was observed in the control group. In the IPF groups, Actinobacteria, Bifidobacteriales, Burkholderiales, Bacteroidaceae, Dorea, Fusicatenibacter, and Ruminococcus ­gauvreauii abundance was low and Enterobacterales, Erysipelotrichaceae, Holdemanella, and Alloprevotella abundance was high compared with those in the control group. When the IPF group using antifibrotic drugs and that not using antifibrotic drugs were compared, only Lachnospiraceae UCG 004 abundance was found to be lower in the patient group receiving antifibrotic drugs. Conclusions: Patients with IPF exhibit higher or lower abundance of certain taxa compared to healthy controls, providing novel perspectives on the pathogenesis and treatment of various illnesses. Examining changes in intestinal microbiota during treatment may guide the clinical strategy for managing adverse effects.