Disclosed is a display device 5 for a work machine having an engine 9, a hydraulic pump 10 driven by the engine, a boom cylinder 3d, an arm cylinder 3e, a bucket cylinder 3f, and other actuators driven by a hydraulic fluid supplied from the hydraulic pump 10, and an operating device 6 for operating the actuators 3d, 3e, 3f. The display device 5 includes an idle state display section 50a for displaying an engine revolution speed N as no-manipulation period operating state information which is related to an engine load that is imposed while the operating device 6 is not manipulated. This makes it possible to inform an operator of the status of the engine load in an idle state for the purpose of prompting the operator to transition into a fuel-efficient state.