Achyranthes bidentata (A. bidentata) Blume is a medicinal herb with the property of strengthening bones and muscles and ensuring proper downward flow of blood in terms of the therapeutic theory of traditional medicine. In the present study, the effect of A. bidentata root extract (AE) on osteoblast function was investigated in osteoblastic MC3T3-E1 cells. AE caused a significant elevation of alkaline phosphatase activity, collagen synthesis, osteocalcin production, and mineralization in the cells (P < 0.05). AE also decreased the production of TNF-α, IL-6, and RANKL induced by antimycin A, mitochondrial electron transport inhibitor. Exposure of MC3T3-E1 cells to antimycin A caused significant reduction of cell viability and mineralization. However, pretreatment with AE prior to antimycin A exposure significantly reduced antimycin A-induced cell damage by preventing mitochondrial membrane potential dissipation, ATP loss, ROS release, and nitrotyrosine increase, suggesting that AE may be useful for protecting mitochondria against a burst of oxidative stress. Moreover, AE increased the phosphorylation of cAMP-response element-binding protein inhibited by antimycin A. Our study demonstrates that A. bidentata could significantly prevent osteoblast damage in aged patients.