To prevent scattering of dust generated when something is cut with a cutter.

In this cutter, a foaming machine to which a liquid foaming solution is guided is provided in a cutter body which includes: a main body provided with a source of motive power; a rotating cutter rotated by the source of motive power with the intervention of a rotating shaft in the main body; a cover having an approximately C-shaped cross section for covering the required peripheral portion of the cutter; and an operating grip portion provided at the main body. A high-speed gas is guided to the foaming machine adjacent the cover to convert the liquid foaming solution into the expanded foaming solution, which is then passed along the cover and ejected from the end of the cover to the peripheral edge of the cutter rotating within the cover.