Recent studies have indicated that Aurora B expression is related to cell proliferation and prognosis in many cancers, but its association with epithelial ovarian carcinoma is not fully understood. Therefore, we examined the Aurora B kinase expression in epithelial ovarian cancer patients. Using immunohistochemistry, the expression levels of Aurora B and phosphohistone H3 (Ser(10)) (mitosis-specific marker) were measured in 156 patients with epithelial ovarian cancer. The expression levels of Aurora B at the protein and messenger RNA levels were examined using Western blotting and reverse transcriptase polymerase chain reaction. In total, 53 tumorous ovarian samples (34.0%) showed Aurora B overexpression, which was significantly higher than that found in the 15 normal ovarian tissue samples (0%, p = 0.006). The overexpression of Aurora B was also significantly higher in cases showing phosphohistone H3 (Ser(10)) overexpression (44.3% vs. 27.4%, p = 0.03). In addition, the expression of Aurora B in poorly and moderately differentiated carcinomas of the ovary was significantly higher than in well-differentiated carcinomas (53.6% vs. 28.2% vs.10.0%, respectively, p = 0.02). The overexpression of Aurora B was significantly higher in cases with lymph node metastasis (p = 0.01) and a positive ascites cytology (p = 0.008). Overall, the Aurora B overexpression group demonstrated a significantly shorter progression-free survival (p = 0.001) and overall survival (p = 0.023) than the Aurora B low expression group using univariate analysis (log-rank statistic). Aurora B is an effective predictor of aggressive epithelial ovarian carcinoma in terms of differentiation, metastasis, and prognosis.