A processing method includes a silicon oxide etching process of performing a plasma etching on a target layer mainly made up of silicon, a silicon oxide layer formed on the target layer and a target object having a previously patterned resist layer formed on the silicon oxide layer, the plasma etching of the silicon oxide layer being performed by using the resist layer as a mask; a deposits removing process of removing deposits generated in the silicon oxide etching process and stuck to the target object; and a silicon etching process of performing a plasma etching on the target layer by a plasma generated from a processing gas containing SF6, O2 and SiF4 while using the silicon oxide layer as a mask.