To provide a method for effectively, economically and equally processing an object with one or more types of liquid and particularly, a method capable of performing a plurality of wet processes without moving the object.

This method for processing an object with liquid includes a process in which trays are accumulated to form a container or arranged in a preformed container and the container or the preformed container inputs an object in a processing system including first and second outlets/inlets for liquid while the method has one or more trays, each of the trays has one or more baskets, and each basket can hold one object (1), a process in which the fluid is caused to continuously flow to the object in a first flowing direction from the first outlet/inlet to the second outlet/inlet for a first period (2), a process for reversing the flowing direction of the liquid (3) and a process in which the liquid is caused to continuously flow to the object in a second flowing direction from the second outlet/inlet to the first outlet/inlet for a second period (4).