Bergamot oil is a kind of citrus oil which contains terpenes, oxygenated compounds, and waxes. Terpenes were removed conventionally by vacuum distillation or solvent extraction. Recently, supercritical carbon dioxide is focused as an alternative solvent for citrus oil processing. A fractionation process of bergamot oil was developed by using a pressure swing adsorption (PSA) concept in supercritical carbon dioxide. The objective of the fractionation is to separate oxygenated compounds from terpenes (deterpenation). The pressure swing operation between the adsorption step at a lower pressure and the desorption step at a higher pressure was carried out with silica gel as adsorbent. Oxygenated compounds were satisfactorily concentrated in the desorption step and the de-pressurization step. A mathematical model simulated the performance of the PSA process. An increase in the pressure ratio (desorption/adsorption) gave high purity, recovery and yield in the desorption step. The purity of 0.84 was obtained in the desorption step at a pressure ratio of 2.5. Model calculations agreed roughly with the experimental results, although the mathematical model was simple.