To permit grasping operation conditions of a working machine at a control station located at a remote place no matter whether or not a trouble has occurred on the working machine, a CPU of a controller arranged on a hydraulic excavator produces operation data in accordance with signals outputted from operation detecting unit such as various sensors. These operation data are stored in a memory unit on the basis of time outputted from a clock unit, for example, depending upon the day. The operation data stored depending upon the day are outputted from an output unit of the controller to satellite communication terminal equipment, for example, when a key switch has been turned on. The operation data are transmitted from the satellite communication terminal equipment to an earth station via a communication satellite and further, are automatically transmitted from the earth station to a control station via a telephone line such that the operation data can be obtained as daily report data or the like by operating a PC at the control center.