Unmanned aerial vehicles (UAVs) are applied to various applications due to its maneuverable flight. Formation flight composed of multiple UAVs has obvious advantages in accomplishing effectively and speedily a task. We propose a formation control of multiple UAVs for omnidirectional patrolling. The formation flight adopts a leader-follower structure. Assumed that motion capture system detects the 3D configuration of formation flight, our method stably and safely controls the formation based on geometric constraint in 3D space. When we fly the leader UAV by remote control according to given flight trajectory, the positions and orientations of follower UAVs are automatically adjusted by our control system so that the leader-follower structure retains the geometric formation. We demonstrate that our proposed method offers excellent formation flight to provide practical omnidirectional patrolling.