A control system composed only of personal computers (PCs) are being developed for the far-infrared free electron laser (FEL) at Institute of Scientific and Industrial Research (ISIR), Osaka University. The system is not only simple and flexible but also cost effective. All the control devices are connected directly to PCs using interface boards in them and the PCs are connected with Ethernet. The software for control consists of three layers; the user interface layer, the database layer and the device control layer. All data for control are transmitted through databases, which are shared by all the PCs using the LAN. Commercially available software is used for the databases and the file sharing, so that it is easy to make and maintain the control software.