Purpose: Atrophy of the internal segment of the left hepatic lobe (S4) has been reported as the first morphological change in chronic liver disease. S4 atrophy was evaluated by B-mode ultrasound, and the results were compared with liver fibrosis index estimated by FibroScan (FS). Material and Method: Fifty-two cases with hepatitis C were examined with abdominal ultrasonography and FS on the same day that they were enrolled. S4 atrophy was evaluated by the distance between the transverse portion of the portal vein and the edge of the S4 (S4 distance). Liver fibrosis was determined as the median of the stiffness on FS as the gold standard. The correlation between S4 distance and stiffness, each blood test date, and spleen index were assessed. Results: The S4 distance became longer with progression of liver fibrosis, i.e., 4.0, 4.2, 7.6, 7.9, and 9.5 mm (mean) for F0, F1, F2, F3, and F4, respectively. There were significant differences between F0 and F2, F0 and F3, F0 and F4, F1 and F2, F1 and F3, and F1 and F4. At a cut-off value of 5.6 mm, it was possible to distinguish F2 or higher with a sensitivity of 91.3% and a specificity of 80.0%. There was a significant correlation between the S4 distance and each blood test data, but not the spleen index. Conclusion: Our findings suggested that S4 distance could serve as a new index for easily and objectively staging hepatic fibrosis. In particular, it was a clinically useful tool in that it could detect fibrosis ≥F2.