Resilience/fault-tolerance has become a key challenge for large-scale parallel systems. To ensure reliability of high performance computing systems, various kinds of techniques have been proposed, such as hardware-level fault-tolerance, checkpointing, replication, algorithm-base fault-tolerance, etc. There are also many software systems to monitor and handle system-failures, e.g. management and job-scheduling system of HPC systems. To evaluate the effectiveness of these systems, it is necessary to provide some kind of tool to inject failures in a HPC system. This paper proposes HPC-SFI, a system-level fault injection tool for HPC systems. Basically, HPC-SFI can generate three kinds of system-failures in a HPC system including in-node faults, failure in the interconnection network and failure of storage/parallel-file system. In addition, HPC-SFI can inject system-faults in pseudo-random model according to pre-defined parameters and probabilities. Preliminary experimental results demonstrate effectiveness of the tool.