A work machine control device for controlling a work machine includes a transport vehicle information acquisition unit and a dumping position specifying unit, the work machine including a swing body and work equipment attached to the swing body and including a bucket. The transport vehicle information acquisition unit acquires position information and azimuth direction information of an unmanned transport vehicle, the position information and the azimuth direction information being detected by the unmanned transport vehicle. The dumping position specifying unit specifies a dumping position for loading earth and sand onto the unmanned transport vehicle based on the position information and the azimuth direction information.