A plasma etching method includes supplying an etching gas containing an oxygen gas and a sulfur fluoride gas at a predetermined flow rate into a processing chamber that accommodates a processing substrate including a silicon layer and a resist layer, and etching the silicon layer with plasma generated from the etching gas using the resist layer as a mask. The plasma etching method further includes a first step of etching the silicon layer while a flow ratio of the oxygen gas to the sulfur fluoride gas is adjusted to a first flow ratio; a second step of etching the silicon layer while decreasing a flow rate of the oxygen gas to decrease the flow ratio to a second flow ratio, which is lower than the first flow ratio; and a third step of etching the silicon layer while the flow ratio is adjusted to the second flow ratio.