The extraction rate of oil from freeze-dried ginger root with supercritical carbon dioxide was measured as a function of CO2 flow rate, particle size, temperature, and pressure. The extraction curves were independent of flow rate in a plot of oil yield versus extraction time. This indicated that the extraction process is controlled by intraparticle diffusion within a particle of ginger root. The extraction rate increased as the particle size decreased due to a decrease in the diffusion path. In the case of temperature and pressure effect, a crossover effect was observed where the higher temperature favored the extraction at 24.5 MPa, while the lower temperature favored the extraction at 10.8 MPa. The shrinking core model was applied to analyze the experimental results, with the effective diffusivity and solubility as fitting parameters. The model successfully fitted the experimental data for larger particle size.