Abstract: A sensor output value estimation device that effectively estimates sensor output values reflecting a response delay of a temperature sensor. The device includes an estimated gas temperature calculation unit for calculating an estimated gas temperature of an engine on a basis of at least a running condition of the engine and a state quantity of the gas in the engine. The device also includes an estimated sensor output value calculation unit for calculating an estimated sensor output value reflecting the response delay of the temperature sensor on a basis of the calculated estimated gas temperature and a pre-stored first model formula specifying a relation among the temperature change time constant of the temperature sensor, the gas flow rate, and the gas temperature.