Larvae of the silkworm (Bombyx mori L.) of two imbred strains (Japanese No. 124 and Chinese No. 124), which are silkworms for egg production, were successfully reared on artificial diets from hatching through the larval maturity. An aseptic technique was also used for one of the experiments. Subsequently, the larvae of the next generation (J. No. 124, C. No. 124, and J. No. 124×C. No. 124) were reared on mulberry leaves throughout. The rate of larval growth and the quality of cocoons were entirely as normal as those obtained with larvae reared on leaves successively for many generations. Thus, the artificial diet could practically be applied for the manufacture of egg production.