This chapter proposes the relay drivers system based on inherently safe design and Failure Modes and Effects Analysis (FMEA). The effectiveness of the proposed method is confirmed by experiment based on the actual driver prototype. Moreover, in order to extend the failure analysis of the CMOS inverter IC considering the self-oscillation phenomenon, this chapter proposes a new anti-oscillation control based on the adding-junction-capacitance concept and a metal shield considering the self-oscillation of CMOSs. This chapter deals with a study of inherently safe components with a fail-safe relay driver of the motor driver system.