Cytological investigations were performed to clarify the karyotype of soma cells and behavior of spermatogonial chromosomes in the spermatogenesis of Tomocerus kinoshitai, Collembola, belonging to Family Apterigota. During the winter the specimens used in this experimentation were kept at constant temperature (25±1℃) and were tested from mid-November to next May. for cytological preparations routine acto-orcein and feulgen methods were employed. Tomocerus kinoshitai has a hexaploid repreductive-line in the male gonads, and its karyotype for both males and females is composed of 12 chromosomes in each somatic cell, and its haploid 6.