AbstractABA‐type block copolymers composed of poly(γ‐benzyl L‐glutamate) (PBLG) as the A component and poly(ethylene oxide) (PEO) as the B component were synthesized by polymerization of γ‐benzyl L‐glutamate N‐carboxyanhydride initiated by primary amines located at both ends of the PEO chain. The morphology examined by transmission electron microscopy using ruthenium tetroxide staining revealed a lamellar type of microphase separation of the copolymers. From circular dichroism measurements in ethylene dichloride solution, as well as from infrared spectra measurements in the solid state, it was found that the polypeptide block exists in the α‐helical conformation, as in PBLG homopolymer. Wide‐angle X‐ray diffraction patterns for the block copolymers depend on the casting solvent and show basically similar reflections as the PBLG homopolymer.