Method for obtaining uniform stream in adsorption column

A method for obtaining uniform stream in an adsorption column is disclosed. This method uses an adsorption column having at least one single-flow passage in which the ratio of the inner diameter of the column to the average particle size of a packing to be packed in the adsorption column is at least 20, and comprises classifying the packing to be packed in the adsorption column and packing the fractions of the packing into the adsorption column in the order of particle size. Thus, a desired substance or substances contained in a mixture can be adsorbed and then separated as a uniform stream in an adsorption column.