The aim of this multicenter retrospective study was to assess the change in liver function in patients with hepatocellular carcinoma treated with lenvatinib. Among 139 consecutive patients receiving lenvatinib treatment between March 2018 and July 2019, 28 patients with Child-Pugh class B and one patient with inadequate patient information were excluded. Remaining 110 patients with Child-Pugh class A were analyzed. The median age of 110 patients was 73 years (IQR 66.7-80) and 88 patients (80.0%) were men. Child-Pugh score was 5 (CP5A) and 6 (CP6A) in 58 (52.7%) and 52 patients (47.3%), and ALBI grade was 1 and 2 in 38 (34.5%) and 72 patients (65.5%), respectively. The deterioration to Child-Pugh class B was found in 43 patients (39.1%) during the lenvatinib treatment. The favorable factors related to preserving liver function were significantly shown to be male, ALBI grade 1, CP5A and BCLC early or intermediate stage in the multivariate analysis. The formation of ascites was found in 32 patients (28.6%). The significant unfavorable factors associated with the formation of ascites were found to be low platelet count and CP6A. Among the 79 patients, there were 36 (45.6%) and 11 patients (13.9%) who fulfilled the criteria for candidate for the post-progression treatment and ramucirumab treatment, respectively. The predictive factors of the post-progression treatment were shown to be ALBI grade 1 and CP5A in multivariate analysis. In conclusion, male, ALBI grade 1, CP5A and BCLC early or intermediate stage were favorable factors related to sustaining liver function and the patients with ALBI grade 1 and CP5A were eligible for the post-progression treatment. Careful screening for ascites was needed in patients with low platelet count and CP6A.