PURPOSE: To maintain easily both columns at the same temp. in a column vessel by adhering a pair of columns on a standard side and a measuring side and at least a part of a sheath.

CONSTITUTION: Columns 1, 2 coated with a stationary phase liquid are adhered integrally with a polyimide resin layer of an outside layer and is cut at a point 3. The stationary phase liquid is introduced from a stationary phase liquid introducing pipe 9 through a capillary 4 to the column 1 side coated with the stationary phase liquid and is discharged through the column 2 and a capillary 7 from a stationary phase liquid discharge pipe 11. The pressure fluctuation of the capillaries 4 and 7 is further prevented in the stage of introducing the stationary phase liquid to the column 1 side coated with the stationary phase liquid on the inside surface and in the stage when the stationary phase liquid flows out of the column 2 side. Since the two columns for chromatographic sepn. are formed to one piece, the same column temp. is maintained on the standard side and measuring side in the column vessel, by which a temp. difference is eliminated.