Unmanned helicopters including multi-rotor drones with flight control functions become widely used in industries. Entry barriers into the drone business become low because COTS drone parts including generic flight control devices and the open-source flight programs can be easily obtained. However, self-development of the original control system may be necessary from the point of view of the custom-function addition and the quality assurance. This lecture introduces the method of mathematical modeling of flight dynamics, control algorithm synthesis, and the implementation techniques of embedded programs into flight control computer for engineers who have no experiences about flight control design of drones.