PURPOSE: To provide a method for extremely advantageously separating and gathering m-xylene from an 8C aromatic hydrocarbon feedstock in a commercial scale.

CONSTITUTION: This method for gathering m-xylene from an 8C aromatic hydrocarbon containing other xylenes by a liquid phase adsorption separation by using a sodium-substituted Y-zeolite as an adsorbent comprises maintaining the temperature of the adsorbent within a narrow range and improving the ability of the adsorbent by the hydration in an adsorption step. The level of the hydration is such a degree that the adsorbent has 3.0 wt.% LOI at 500°C temperature, and the adsorption temperature is within the range of 100-145°C. In a preferable example, the Y-zeolite is substituted with both of lithium and sodium in the interior.