This study was to identify the modifications of brain neurosecretory cells at the developmental stages of the silkworm (Bombyx mori). Brains were dissected out at late larval, pupal and adult stages and stained with paraldehyde fuchsine (PAF-Gabe) for histological examination. Three types of neurosecretory cells in pars intercerebralis (PIC) and one type in pars lateralis (PL) were determined by staining properties with paraldehyde-fuchsine (PAF-Gabe). In addition to morphological modifications occurred in brain during development, some changes were defined at localizations of neurosecretory cells. Some changes were observed by staining properties of these cells in depend on their secretory activities too. It was typical that NSH-1 cells of PIC have a cytoplasmic vacuole containing dense material. However, it was not identified what the material is in these vacuoles. It was considered that there were occurred some changes and increased or decreased on their neurosecretion material in the neurosecretory cells relation with their locations and staining properties during development in B. mori.