Construction machinery is capable of prompting an operator to control or operate the machinery to improve fuel consumption. The fuel consumption per time or the fuel consumption per work amount is measured, and an image showing a difference between the measured fuel consumption per time and a set fuel consumption per time or between the measured fuel consumption per work amount and a set fuel consumption per work amount is displayed on a display device (30). When the measured fuel consumption per time is larger than the preset fuel consumption per time or the measured fuel consumption per work amount is larger than the set fuel consumption per work amount, an indication for prompting the operator to improve the fuel consumption is displayed on the display device (30).