PROBLEM TO BE SOLVED: To provide an oscillation dehydration method capable of efficiently performing generation of cake through filtering of liquid-containing raw material within a processing vessel as well as breaking and oscillation dehydration treatment of the cake.SOLUTION: This invention relates to an oscillation dehydration method for obtaining a powdery product from liquid-containing raw material through a filtering step and a dehydration step under application of a vertical type oscillation dehydration machine D in which a filtering material 51 is installed at an upper part in a treatment container 11. This method comprises the filtering step and the dehydration step. The filtering step is carried out in such a way that the treatment container 11 is reversed to be set in an inverted state and after the liquid-containing raw material is fed at a raw material feeding port 33 formed at the bottom part side of the container, cake C is accumulated on the filtering material 51 through the differential press
