The present invention relates to a method and an apparatus for the separation of C4 olefins (butene-1, trans-2-butene, cis-2-butene, etc.) and C4 paraffins (normal butane, isobutane, etc.) from a C4 hydrocarbon mixed gas including butene-1, trans-2-butene, cis-2-butene, normal butane, isobutane, etc. The method of the present invention produces C4 olefins with high purity by introducing a gaseous C4 mixture into the adsorption tower loaded with adsorbent selectively adsorbing olefins to adsorb C4 olefins and to discharge C4 paraffins to the outlet of the tower, desorbing C4 olefins adsorbed on the adsorption tower with a desorbent (C5 hydrocarbon, C6 hydrocarbon, etc.), and then separating the C4 olefin and the desorbent by a distillation process. The apparatus of the present invention is composed of several adsorption towers loaded with an adsorbent which selectively adsorb olefins and two distillation towers for the separation of the mixture gases of olefins/desorbents and paraffins/desorbents respectively, The basic operating process of the adsorption tower comprises a adsorption step of selectively adsorbing C4 olefin from the feeding mixture, a C4 olefin rinse step of removing a small amount of C4 paraffins adsorbed together with C4 olefins, and a desorption step of desorbing C4 olefins by using a desorbent, and further comprises a pressure equalization step, a cocurrent depressurization step, and a accumulation pressure step in order to increase the yield and concentration of olefins depending on the operation pressure of the adsorption tower. The desorbent discharged from the process together with olefins or paraffins is separated in the distillation tower and then recycled.