Design of an adaptive dynamic feedback-linearization control law for a quadrotor unmanned aerial vehicle under uncertain parameters is presented. Because the quadrotor carries rotational speed-varying thrusters, it has the advantage of simple mechanism compared to the pitch-varying thrusters. However, it is subjected to slow dynamics in thruster and suffers from uncertainties in efficiency due to power subsystem. Additionally, parametric uncertainties tend to exist such as thruster misalignment, mass, and inertia. The control law is targeted to tracking reference trajectories under such uncertainties. Dynamic feedback-linearization method is employed primarily to produce the small-bandwidth thruster signal. A dynamic observer is used to estimate the states of feedback-linearized system, and Lyapunov-based update laws are derived to compensate for uncertain parameters. The controller and its performance are evaluated using a nonlinear, six-degree-of-freedom dynamic model of a quadrotor unmanned aerial vehicle with a thruster model in the simulation. The results illustrate that the proposed control law enhances tracking performance even with slow and misaligned thruster.