This paper proposes fault tolerance service to satisfy quality of service (QoS) requirement in grid computing. Since the failure of resources affects job execution fatally, fault tolerance service is essential in grid computing. And grid services are often expected to meet some minimum levels of QoS for desirable operation. In order to provide fault tolerance service and satisfy QoS requirements, we expand the definition of failure, such as process failure, processor failure, and network failure. And we propose fault detection service and fault management services.