The invention provides a plasma etching method, a plasma etching device and a computer storage medium, which can inhibit the application of the processing gas with high corrosivity and form a pattern with the defined shape in a good precision. A plasma etching method includes etching a silicon layer formed on a substrate to be processed through a patterned mask layer by using a plasma of a processing gas. The processing gas contains at least a CF3I gas, and during said etching the silicon layer, a radio frequency power is applied to a lower electrode mounting the substrate thereon such that a self-bias voltage Vdc for accelerating ions in the plasma is equal to or smaller than 200 V.