A display system for a working machine displays basic information at all times and, in case of an abnormality, displays the details of the warning in addition to the basic information to enable an operator to reliably recognize details of the warning. For example, a first warning display function, upon receiving an abnormality information signal relating to a charge warning, displays an appropriate warning icon in a warning icon display region. A simplified basic-information display function, then displays simplified basic-information images and a second warning display function displays, in a free area of the display, a second warning message inclusive of a “Charge warning” message as display details of the warning icon, and of character information relating to a simplified remedial action. The operator can then reliably recognize the “Charge warning” and understand its details as well, by viewing the second warning message in addition to the warning icon.