To further improve the convenience of a cutting tool, by easily opening and closing a tool holder, quickly and simply attaching and detaching a cutting tool, and facilitating switching of use between the moving cutting work in the state of holding the cutting tool in hands and the stationary cutting work in the state of fixing the tool at a predetermined position.

A base plate 2 for placing and fixing a material 26 to be cut substantially horizontally is provided with the tool holder 6 for removably holding a cylindrical body 13 in the handy cutting tool 11 having a rotary blade with the center line of the body laid along the longitudinal direction. The tool holder includes: upper and lower holders 17, 16 holding the outer peripheral surface of the body in the cutting tool from the upper side and the lower side, the lower and upper surfaces of which are opened; and a tool operating handle 7. The lower holder includes: a lower holder base plate 16a narrower than the lateral width of the body in the cutting tool; and a pair of lower holder side plates 16b obliquely erected from the lower holder base plate to support the both right and left side lower parts of the body of the cutting tool, respectively.