This research project is concerned with the morphological characteristics, the wing beating behavior, and the aerodynamic characteristics of a flying animal. The wings of the dragonfly, Sympetruin infuscatum, the gadfly, Tabanus rufidens, the fly, Parasarcophaga crassipalpis, and the vinegar fly, Drosophila lutea were observed microscopically making use of the scanning electron microscope. Several cross section of insect costa were observed, and the image processing of the electron micrograph was conducted on a personal computer. It was found that the costa varies in shape and size corresponding to the location of wing. With respect to the structure of the flight feather, the pigeon feathers were observed microscopically using the scanning electron microscope. A three dimensional motion analysis system revealed the wing motion of the flying animal. The experimental system composed of two high speed video cameras, a motion grabber system and a personal computer, analyzed the wing motion in three dimensions. The free flight of theflying animal was analyzed. The relationship between the insect flight and its wing structure was reveald. The free flight behavior of the Java sparrow was clarified, that is, the time variation of the displacement and velocity on the bird's wing was obtained quantitatively. Wing path and flapping of the bird were obtained in three dimensional expression.When the flight feathers of the Java sparrow were exposed in the uniform smooth wind, bending of the flight feather occurs, and bending characteristics of the flight feather showed the anisotropy in the wind direction. Each flight feather has its own bending characteristics.