Spawning behavior of Octopus vulgaris has been known as the mystery in marine biology. Because mother octopus makes fine egg masses in the underwate and narrow space, we could not observe this behavior with naked eyes. Especially how to form each egg mass is in interest. We used endoscopy (Olympus Video Imagescope IV-11D2-30) designed for industrial use to observe this phenomonon. It was successful that Octopus spawning behavior in the octopus pot was clearly recorded in detail. A few eggs with egg stalks were ejected through its funnel in one jetting. Eight small suckers around the mouth caught the eggs, and twisted their stalks. It is certified that " egg mass forming part" is the just around the mouth. Imagescope visualized spawning behavior of benthic animals, then this method would be the powerful tool in marine biology and fishery science.
