To provide a processing tool and a processing method for the processing of electronic materials such as a piezoelectric element, silicon or gallium arsenic or the like and the other substances.

A crystal plate 13 obtained from electronic materials such as a crystal plate 13 or silicon or gallium arsenic or the like through the polishing process with a both-side polishing machine, or a single-side polishing machine or the other polishing machine is then subjected to chemical etching from the single side or both sides to eliminate the element in amount of several tens of μm or so. Thereafter, the polishing process is conducted again in the amount of several μm generated by chemical etching process such as RIE (Reactive Ion Etching) with the both-side polishing machine, single-side polishing machine, float polishing machine or the other polishing machine. Thereafter, the final etching process such as RIE process is conducted from both sides. Accordingly, an electronic material as thin as 14 μm having the diameter, for example, of 2 inches and high accuracy can be produced.