An insoluble chiral membrane of one-handed helical multihydroxy poly(phenylacetylene) without the coexistence of any other chiral moieties has been synthesized by in situ complete removal of a one-handed helical poly(phenylacetylene) having multihydroxymethyl groups and chiral pinanyl groups in each polymeric unit in the membrane state. Although the enantiopermselectivity was decreased, the permeability increased four times by removing the chiral groups. In comparison with the corresponding poly(phenylacetylene) having no hydroxymethyl groups and chiral pinanyl groups, the loss of enantiopermselectivity was much lower. It is believed that the multihydroxy groups could maintain the main-chain chirality or enhanced interaction with permeant.