A needle roller bearing is an essential machine element for the precise operation of an automobile engine rocker arm. The fuel efficiency, noise, durability, and power of the engines can be improved by mounting the needle roller bearing on the rocker arm. In particular, as the driving performance and power of automobiles improve, it is necessary to design and manufacture needle roller bearings to prevent accidents caused by issues such as bearing failure from fatigue, wear, and fracture, even under extreme operating conditions. In this study, an automobile engine rocker arm was modeled, and the load acting on the needle roller bearing was calculated using a multi-body dynamic simulation (MBDS). In addition, the static safety factor and dynamic life were evaluated according to ISO 76 and ISO/TS 16281 using the calculated load and bearing parameters. Furthermore, the effects of the bearing roller profile on the bearing contact stress distribution were analyzed, and an optimal roller profile was chosen. Finally, the safety of the bearing roller was quantitatively evaluated by comparing the loads acting on each roller with the roller capacity.