A gasification power generation system provided with a carbon dioxide separation and recovery device (200) comprising: a carbon dioxide separation and recovery device (200) having: a shift reactor (5) to convert carbon monoxide contained in fuel gas into carbon dioxide; a carbon dioxide absorption tower (37) to produce fuel gas; and an absorption liquid recycling device (38) to recycle an absorption liquid; and a gasification power generation system having: a gas turbine device driven by burning the fuel gas; an exhaust heat recovery boiler (20) having a drum (30,31) to generate steam; and a steam turbine (23) driven by the steam generated by the drum (30,31); wherein an evaporator (6) to generate steam is disposed downstream of the shift reactor (5), a steam line to supply a steam mixer (4) disposed in a fuel gas line upstream of the shift reactor (5) with the heated steam generated by the evaporator (6) is provided, and the heated steam supplied through the steam line is allowed to flow from the steam mixer (4) into the shift reactor (5) as shift steam together with the fuel gas.