A sintered diamond tool which is excellent in resistance to deposition and to breakage and has high strength. A sintered diamond tool (20) comprises a tool substrate (22) comprising sintered diamond and a surface layer (21) formed on the surface of the tool substrate (22). The surface layer (21) comprises at least one of silicon, an oxide of silicon, a carbide of silicon, a nitride of silicon and a solid solution thereof. The tool substrate (22) comprises an internal part (22b) which contains an iron group metal in a first content and a surface part (22a) which surrounds the internal part (22) and contains an iron group metal in a second content being lower than the first content.