To improve yield of a semiconductor device by suppressing minute foreign materials from sticking to a semiconductor wafer surface, in a wet etching process for a semiconductor wafer.

Related to a series of wet etching processes wherein a plurality of semiconductor wafers 2 are submerged in a chemical liquid bath 1 at the same time and are submerged in a washing bath for washing, a partition 3 which separates the plurality of semiconductor wafers 2 is provided at least at a gas-liquid interface part when the semiconductor wafer 2 is taken out of the chemical liquid bath 1 as well as at delivery of it to the washing bath 1.