The functional safety focuses on the hardware, software, and human which construct the safety-related control system, and specifies the requirements corresponding to the severity of the damage foreseen when the safety-related control system becomes malfunction. In order to achieve the functional safety, practical use of the basic researches accumulated in the past in fields, such as dependability, reliability, electricity, machinery, software, and management of an organization, is essential. This paper describes the relation of the technology of dependability and risk management fields across boundaries in functional safety.