Background/Aim: The frequency of hepatocellular carcinoma (HCC) in patients with good hepatic reserve function has been increasing in Japan along with the progression of antiviral therapies and aging of the society. We evaluated the usefulness of modified albumin-bilirubin (ALBI) grade as a tool for assessment of hepatic reserve function. Materials/Methods: We enrolled 6,649 naïve HCC patients treated from 2000 to 2017 and divided them into training (Ehime Prefecture group: E group, n = 2,357) and validation (validation group: V group, n = 4,292) cohorts. Child-Pugh classification and ALBI and modified ALBI (mALBI) grading were compared using with Japan Integrated Staging (JIS), ALBI-TNM (ALBI-T), and mALBI-T scores, which were calculated based on TNM stage and each assessment tool, retrospectively. Results: In the E group, Akaike’s Information Criterion (AIC) and c-index values for mALBI-T (13,725.2/0.744) were better as compared to those of ALBI-T (13,772.6/0.733) and JIS score (13,874.7/0.720), with similar results observed in the V group (mALBI-T: 27,727.4/0.760; ALBI-T: 27,817.8/0.750; JIS: 27,807.5/0.748). Although there were some significant differences between the groups with regard to clinical background factors (age, etiology, tumor size, tumor number, treatment modalities), for all patients the AIC and c-index values of mALBI-T (45,327.1/0.755) were also better than those of ALBI-T (45,467.7/0.744) and JIS scores (45,555.8/0.739), indicating its superior stratification ability and prognostic predictive value in patients with HCC. Conclusion: The detailed stratification ability of mALBI grade for hepatic reserve function is suitable for the recent trend of HCC patients, while mALBI-T may provide a more accurate predictive value than existing total staging scoring systems.