A new silkworm variety, Chunsujam, for spring rearing season is F$_1$ hybrid between Japanese race Jam145 bred by 8459/8711 and Chinese race Jam146 by 8544/M8626. Jam145, Japanese parent of the Chunsujam, showed high GCA in pupation rate and Jam146, Chinese parent, showed high GCA in pupation rate and single cocoon weight. In the local adaptability test performed at 8 local areas in spring of 1999, Chunsujam was 5% higher in larval weight, 3% in single cocoon weight, and 4% in cocoon yield from 10,000 of the 3rd molted larvae, respectively, than the check variety Baegokjam.