Carbon capture is a promising technology for carbon dioxide (CO₂) removal from large stationary CO₂ sources. The effects of carbon dioxide capture process on output efficiency of fossil power plants were investigated. Supercritical pulverized coal and integrated coal gasification combined cycle (IGCC) were assumed as model coal-fired power plants for this investigation. Heat-driven and pressure-driven CO₂ capture processes such as chemical absorption and physical adsorption were assumed for CO₂ capture process. In this study, these technologies were evaluated and compared under the unified basis and conditions by using the commercial process simulator. For IGCC plant, the efficiency penalty by installing water-gas shift reaction was also investigated. Gross and net power generation, efficiency and the efficiency penalty by CO₂ capture process were calculated. Heat duty for CO₂ capture process and CO₂ compression conditions were varied, and those effects on the efficiency penalty were obtained. The results provide a guideline for development of CO₂ capture process of power plants.