To provide a tool holding device in which the positioning of an angular position when mounting a tool is easy and by which the occurrence of vibrations during working can be suppressed.

The tool holding device is provided with a mounting holder 2, a tool holder body 4 attachably/detachably mounted to the mounting holder 2, a collet holder 6 mounted to the tool holder body 4, and a working tool 50 freely attachably/detachably mounted to the collet holder 6. The tool holding device is also provided with a first angular position holding means for holding the tool holder body 4 to the mounting holder 2 at a prescribed angular position and a second angular position holding means for holding the working tool 50 to the tool holder body 4 at a prescribed angular position.