Abstract: A process for chromatographic fractional separation of a ternary or more fluid feed into at least three fractions according to a simulated moving bed procedure in a system wherein the simulated moving bed packed with an adsorbent is provided with a circulatory channel having a shutoff position where the circulation of the system can be shut off, comprises step (1) of feeding fresh fluid feed into the system on the downstream side of the shutoff position while withdrawing a fraction(s) of a component(s) having a medium affinity for the adsorbent from an adsorption zone(s) located upstream of the shutoff position, which step (1) is repeated alternately with step (2) of separately withdrawing fractions of components fractionated into respective adsorption zones remaining after the step (1) by feeding a fluid desorbent into the system with sequentially shifting the position of feeding the fluid desorbent and the positions of withdrawing enriched fractions, corresponding to the migration of the respective adsorpti