Abstract: A work machine includes a vehicular body, a work implement supported on the vehicular body, and an engine which is a drive source of the work implement. The control device of the work machine includes a rotation speed setting member manually operable for setting a target rotation speed of the engine and a controller that selectively carries out any one of ordinary control and intervention control. When ordinary control is carried out, an engine controller controls the engine at the target rotation speed based on an operation onto the rotation speed setting member. When intervention control is carried out, an intervention controller estimates contents of works by the work implement. The engine controller sets the target rotation speed corresponding to the estimated contents of works and controls the engine at the set target rotation speed regardless of an amount of operation onto the rotation speed setting member.