The present invention provides an organic ultra-thin film firmly fixed to a substrate with the film thickness ranging from tens of nm to hundreds of nm. The organic ultra-thin film comprises polymers fixed on a substrate by M.sub.2--O--A-- bond in which A represents an Si, Ge, Ti, Sn or Zr atom in the polymer, and M.sub.2 represents an atom in the substrate) or by a coordinate bond, the polymers are combined with each other by --A.sub.1--O--A.sub.1'-- bond in which A.sub.1 and A.sub.1' are Si, Ge, Ti, Sn, Zr or S or by a coordinate bond.