Disclosed are: a method for production of a polyisocyanide derivative having a stable helical main chain structure with a right-handed or left-handed helix or a mixture thereof from a single type of monomer by polymerizing an aromatic isocyanate having a substituent harboring a structure --CONH in the aromatic ring and a hydrophobic moiety having 6 or more carbon atoms in a polymerization solvent, wherein the direction of the helix depends on the polarity of the polymerization solvent; a poly(aromatic isocyanide) derivative produced by the method; and an aromatic isocyanide which is useful as a monomer for use in the production of the poly(aromatic isocyanide) derivative.