The analysis of the accumulated data from the spawning surveys on Japanese sardine revealed that distribution densities of both eggs and prelarvae of the fish had been higher in the waters offshoreside of the Kuroshio axis than its inshoreside in the waters east of Cape Shionomisaki since 1984. The largest catches of sardine eggs by plankton net also occurred on the offshoreside of the Kuroshio in the same period. These phenomena were conspicuous in 1988 and 1990 in which the locations of the largest catches were far distant south of the Kuroshio axis.