Maskless dry etching of Mn-Zn ferrite in dich1orodif1uoromethane (CC12F2) by Ar+-ion laser (514.5 nm-line) irradiation has been investigated to obtain high etching rates and aspect-ratios of etched grooves. The etching reaction was found to be thermochemical and caused by Cl radicals thermally decomposed from CCl2F2 gas. High etching rates of up to 360 μm/s, which is about one order of magnitude higher than that in a CCl4 gas and even higher than that in a H3PO4 solution, have been achieved. A high aspect-ratio of up to 12 was obtained. Definite gas pressure and dwell time are necessary to fabricate a smooth groove.