Recently, there have been demands for greater functional diversity and higher performance in the information technology (IT) infrastructure and mobile communication products. As a result, the complexity and scale of product design in the product development phase have increased. In addition, development periods need to be reduced so products can be marketed sooner These requirements have rapidly increased the need to efficiently simulate and analyze in order to achieve optimum designs and verification. To satisfy these requirements, the grid middleware CyberGRIP has been developed to make it possible to integrate heterogeneous computing resources that are geograplucally dispersed in the enterprise and virtualizes them as a single computer system for the users. The CyberGRIP has the following functions: organic job control, resource monitoring, brokering with jobs and most appropriate resource to execute the job, and batch system for personal computer Moreover, CAD-Grid system has been constructed, by using CyberGRIP, to quickly perform computationally intense simulations in the product development phase. This system has been used to simulate a mobile communication system and others. This paper describes the grid middleware CyberGRIP and grid computing environment CAD-Grid, its structure, the system simulation to which CAD-Grid was applied, and the application results.