A new silkworm variety, Kumhwangjam, with a sex-limited cocoon color for spring rearing season is F$_1$ hybrid between Jam 309, a Japanese race bred from Y1/9153, and Jam 310, a Chinese race from Y1/8586. In the local adaptability test performed at 8 local areas in spring rearing season of 2003, major characteristics of Kumhwangjam were mainly similar to those of the check variety Kumokjam. The new silkworm variety, Kumhwangjam, showed a sex-limited cocoon color: yellow for female and white for male with elliptical cocoon shape. This sex-limited cocoon color can be used as a valuable marker for discrimination between female and male for various purposes.