Abstract: A fuel-efficient hydraulic fluid has a lower viscosity than a standard hydraulic fluid, a pressure loss decreases, and thus, when control based on a standard model is exercised, the speeds of various actuators increase. However, the speeds need not be increased beyond the speeds of the standard model. Instead, it is preferred that fuel efficiency be improved. As a result, an engine revolution speed decreases by 50 rpm and a pump torque decreases by 5%. This reduces an engine output. Therefore, when a hydraulic fluid is changed from the standard hydraulic fluid to the fuel-efficient hydraulic fluid, the fuel efficiency can be improved while maintaining operability equivalent to that of the standard model. Hence, the fuel efficiency can be improved while maintaining the operability when an item affecting the fuel consumption is replaced. In addition, the settings can be changed with ease by a service technician.