Optical observations of flickering aurora by a high-speed imaging photometer system were carried out at Syowa Station in 1998. A comparison between observed parameters of flickering aurora and theoretical values of dispersive Alfv¿n waves indicates that observed flickering aurora would be produced by electron flux modulations by electromagnetic ion cyclotron waves or inertial Alfv¿n waves in the auroral acceleration region located over the altitude range of ~2000--5000 km. Interference wave patterns of two dispersive Alfv¿n waves in a resonance cone can explain the observed temporal and spatial structures of flickering aurora; flickering columns (or spots) remain in almost the same location during their lifetime and that their shapes become indistinguishable every half flickering period at the timing of the interchange of the bright and dark columns (or spots).