A gas circuit breaker (GCB) requires high speed motion and high reliability because it is a safety apparatus that protects devices by breaking a circuit instantly when an abnormal current flows in a power transmission line. GCB motion must be analyzed to improve GCB development efficiency and reliability. Recently, a GCB has been developed that has a double-break and a single mechanism for ultra-high voltage. Thus, this GCB, which is driven at high speed by a large driving force, requires motion and load of each part to be accurately estimated. Therefore, we focused on the difference in motion between an interrupter and a hydraulic operating mechanism and established a simulation model that divides moving parts between the interrupter and hydraulic operating mechanism into some portions and connects the portions by a non-linearity function of stiffness and a linkage mechanism. Moreover, we established GCB integrated motion analysis using hydraulic analysis of motion in the hydraulic operating mechanism, electromagnetic analysis in solenoids, puffer pressure analysis in the interrupter, and a simulation model of the interrupter and hydraulic operating mechanism. Using this integrated analysis, we confirmed this analysis can definitely analyze displacement of motion and load of each part with sufficient accuracy. Furthermore, we established a method for designing an operating mechanism using this analysis and designed an operating mechanism to meet the required breaking performance and low load characteristic.