Abstract Resumption of arrested development in the silkworm at the embryonic stage is parallel to the activation of TIME (Time-Interval-Measuring-Esterase), which initially exists as complex form with PIN peptide. TIME-PIN complex dissociates by exposing to low temperatures, then PIN was separated by ultra-filtration and chromatography. Amino acid sequences of 6 peptides, as PIN components varying from 28 to 38 residues, were determined by amino acid sequencer and by HPLC-ESI/MS. Their sequences are the parts of a common and the longest sequence of PIN. which is SIFMT KQHSQ DDIIQ HPLDY VEQQI HQQKQ KLQKQ TLN.