A clad is produced by polymerizing methyl methacrylate and (meth)acrylic
acid ester having alicyclic hydrocarbon group. A core is produced by an
interfacial-gel-polymerization method. A first covering layer having a
thickness being less than 500 .mu.m is formed on an outer surface of the
clad to produce a single-fiber optical cable. A plurality of the
single-fiber optical cables are bundled. A gap between the single-fiber
optical cables is infused with a filler. The bundled single-fiber optical
cables are covered with a second covering layer to produce a multi-fiber
optical cable. Since the covering layer is thin, the multi-fiber optical
cable has excellent flexibility and reduced bending loss.