The present invention relates to an adenosine deaminase inhibitor and a novel Bacillus sp. strain which produces it. Particularly, the present 5 invention relates to the adenosine deaminase inhibitor, and the novel Bacillus sp. IADA-7 producing the above adenosine deaminase inhibitor. The adenosine deaminase inhibitor of the present Invention shows superior antibacterial and anticancer activities to the previously reported adenosine deaminase inhibitors.