Background: Eribulin therapy has recently attracted attention from various viewpoints, including quality of life, and is considered a standard therapy for inoperable or recurrent breast cancer. Although a reduction in renal function reportedly decreases total eribulin clearance, its association with dose-limiting toxicity and the reduction of neutrophils remain unclear. Aim: This study was aimed at analyzing the association between decreased renal function prior to eribulin administration and the occurrence of neutrophil reduction and time to treatment failure in patients with breast cancer. Methods and Results: We retrospectively assessed patients with breast cancer, who underwent eribulin therapy between July 2011 and March 2018. Multivariate analysis revealed creatinine clearance <70 mL/min and serum albumin levels <3.9 mg/dL as predictive factors for neutrophil reduction. Even on increasing the relative dose intensity by these factors, no difference in time to treatment failure was observed, suggesting that treatment efficacy is potentially unaffected. Conclusions: For continuous eribulin therapy, eribulin may need to be administered to individual patients in accordance with renal function and albumin levels before treatment initiation.