This study evaluates the strength of tapered roller bearing loaded vibrations. We modeled tapered roller bearings with a flexible multi-body model and calculated the retainer stress by mechanical simulation. The simulation results show that retainer stress increased when the rollers vibrate in the yaw direction, and the largest part of the stress was the root of the retainer bridge. We also evaluated the fatigue strength based on the calculated stress of the retainer with this simulation. However, since such a simulation with a flexible multi-body model was very time-consuming, we could not calculate the stress in various conditions. To solve the time-consuming problem, we confirmed that the major frequency of the stress in the retainer bridge's root is below the first natural frequency of the retainer and found that this simulation can be calculated by the solid body model to save time. We calculated the root's stress of the bridge per unit force by static analysis with the force calculated by solid body model analysis. Using this solid body model, we calculated the force between the retainer and the rollers in various conditions and learned that it increased depending on the vibration acceleration, the rotation speed of the inner race, and the radial force; it did not increase depending on the rotation direction of the inner race. We also identified the acceleration level at which the bearing is likely to experience fatigue failure.