The present invention provides a catalyst temperature control device to control a temperature of a catalyst which influences emission performance of an internal combustion engine. A plurality of temperature measurement points are disposed continuously or dispersedly at least in a flow path direction inside the catalyst. The temperature measurement points can include actual measurement points where temperature sensors are disposed, and virtual measurement points where temperature sensors are not disposed. A control point is selected from the plurality of temperature measurement points in accordance with operation conditions of the internal combustion engine, and a target value of the temperature of the catalyst is set. A manipulated variable of the internal combustion engine is determined based on a difference between the temperature at the control point acquired by actual measurement or estimation and the target value, and the internal combustion engine is operated in accordance with the determined manipulated variable.