This chapter covers the design principles of magnetic actuated catheter robot and is outlined as follows. Section 1 discusses key fundamental principles to design for an electromagnetic catheter/guide wire type surgical robot. The clinical perspectives are covered in Sect. 1.1 and in Sect. 1.2 the overarching electromagnetic theory is mentioned. Electromagnetic systems can be further decomposed into the stators (stationary wound coils) and actuators (moving part usually consists of permanent magnet), where the stators can be interpreted as the input and the actuator the output. Section 2 will cover the design consideration of stators and Sect. 4 the design principles of the actuators. Sections 2 and 3, aim to provide the reader with an intuitive approach to designing their own electromagnetic system. Section 3 will further exemplify principles covered in Sects. 2 and 3 with a fabricated prototype from our lab. These electromagnetic catheter systems can be classified by many parameters; one important parameter is the bending angle and will be addressed in Sect. 4. The use of this angle is demonstrated for a surgical context. This chapter concludes in Sect. 8, providing an overview of the works presented and the future directions.