Inhibitory activity of organobismuth compounds, triarylbismuthanes 1 and their dihalides 2 and 3, was examined against jack bean urease. Besides triarylbismuth dichlorides 2, triarylbismuth difluorides 3 and bismuthanes 1 exhibited the activity. Of all these compounds, triphenylbismuth difluoride 3a and tris(4-fluorophenyl)bismuth dichloride 2b showed the highest activity. These results indicate that generation of the inhibitory effect is not always governed by the Lewis acidity at the bismuth center. Such a tendency of inhibition by the organobismuth compounds is in good accord with that observed in the antibacterial activity against Helicobacter pylori, suggesting that H. pylori-produced urease may be a therapeutic target by bismuth-based drugs.