Typhoon Cora, 1969, took the extratropical appearance over the Japanese Islands. This aspect is analyzed from the view-point that Cora is the compound system of tropical and extratropical cyclones. The synoptic analyses show that the participant extratropical cyclone pre-existed independently far from Cora and approached Cora to form the compound system with her, and that it usurped Cora at last, resulting in her apparent extratropical transformation. This aspect is different from those, previously investigated as the complex system, in which the participant extratropical cyclone is induced on the pre-existing front which invades into the inner region of typhoon area. The synoptic behavior of participant extratropical cyclone of the compound system is brought into focus to confirm the condition favorable for its deve'opment.