Oriental medicine uses many herbs with biological activity. Among these, some have anti-inflammatory activities, but their action mechanisms have yet to be fully elucidated. Therefore, in this study, we harvested mouse bone marrow cells (BMs) and treated them with lipopolysaccharide (LPS), after which they were treated with the extracts of four medicinal herbs. The metabolic activity, cell death ratio, and tumor necrosis factor (TNF)-alpha production of the BMs was then evaluated. Among the four medicinal herbs, Caesalpinia sappan (CS) significantly decreased the metabolic activity, mitochondrial membrane potential of BMs, and production of TNF-alpha, especially in the presence of LPS. Moreover, CS increased the cell death of BMs stained with propidium iodide. Taken together, these findings indicate that CS inhibited the biological activities of LPS-treated BMs in multiple assays, confirming that CS has anti-inflammatory activity.