To reduce the cost of a construction machinery including a display device for displaying various information, such as captured image of a camera or machine information, on a monitor screen image, when the information displayed on the monitor screen image is configured to be automatically switched according to the operation of the construction machinery.

The control portion 14 compares image data captured by a rear camera 8, and determines an operation of a hydraulic shovel 1 based on the difference. When the hydraulic shovel 1 is determined to be performing a reverse movement, a left swiveling or a right swiveling, the control portion 14 selects the captured image of the rear camera 8 or a right camera 9 so as to correspond to the movement, and causes the display device 10 to display it on the monitor screen image 12.