This paper deals with the attitude control of a self-made VTOL vehicle which is round shape and has four fans and motors. Although hovering mechanisms are suitable for field work at a mountainous region or a building site etc., it is known that modeling the structure of the plant is quite difficult due to its unstable or uncertain characteristics. So, a robust controller is requried in order to cope with these uncertainties. WE first model the structure of the plant under the actual hovering setting and then determine the uncertainty of the acquired mathematical model by using system identification method as exactly as possible. We adopt the $H^{infty}$ theory as a control algorithm because of its availability, and the structure of two-degree-of-freedom is used as a basic feedback control system to improve the transient response of the plant. Finally, we show the appropriateness of the designed controller through simulations and experiments. That is, the proposed VTOL system is able to maintain its roubust performance in spite of parameter variations and existing disturbances..