A working machine includes a pipeline disposed along a side deck in a front-back direction and connecting a hydraulic pump and a control valve. The hydraulic pump is mounted at a back portion of an upper frame of an upper rotating body and the control valve is mounted at a front portion of the upper frame. In the working machine, a reinforcing member having a space for accommodating the pipeline is mounted in the front-back direction of the side deck to an outermost side of the side deck in a widthwise direction thereof. The pipeline is passed through the reinforcing member.