In this research, an attitude update method using rotation matrix is verified and validated. First, a continuous time rotation matrix update formula is derived newly without any assumptions or approximations. The continuous time method is compared with other existing methods that use quaternion or Euler angles, by a computation experiment of a Matlab Simulink program. The discrete time version of the method is derived and implemented on a quadcopter and validated through a real flight. For a more severe experiment condition, the flight control computer is separately rotated quickly multiple times by hand. From the experimental result, the attitude angle difference between this method and the quaternion method is evaluated.