NOVELTY - A cyclic olefin copolymer contains repeating unit (A) derived from non-conjugated diene (I), repeating unit (B) derived from cyclic non-conjugated diene (II) and repeating derived (C) from cyclic olefin (III).    USE - Cyclic olefin copolymer is used for varnish and crosslinked component for molded product e.g. film, sheet, high frequency circuit board and substrate for liquid crystal display (all claimed). Uses include but are not limited to optical fiber, optical waveguide, optical disk substrate, light filter, lens, adhesive agent for optics, coating material for organic electroluminescent element, base film material for solar cell, etc.    ADVANTAGE - The crosslinked component formed using cyclic olefin copolymer has excellent solvent resistance, heat resistance, mechanical strength, gas-barrier property and transparency.    DETAILED DESCRIPTION - A cyclic olefin copolymer contains repeating unit (A) derived from non-conjugated diene of formula (I), repeating unit (B) derived from cyclic non-conjugated diene of formula (II) and repeating derived (C) from cyclic olefin of formula (III).    R300=H or linear or branched 1-29C hydrocarbyl;    u,w=0 or 1;    v=0 or positive integer;    R61-R78,R'a1,R'b1=H, halo, 1-20C alky, 1-20C halo alkyl, 3-15C cycloalkyl, or 6-20C aryl;    R104=H or 1-10C alkyl;    t=0-10;    or R75+R76=ring;and    or adjacent R75-R78=ring.    INDEPENDENT CLAIMS are included for the following:    (1) manufacture of cyclic olefin copolymer, which involves reacting organometallic compound (m1), organoaluminoxy compound (m2) and compound (m3) with transition metal compound of formula (IV), obtaining ion pair, and addition-polymerizing monomers of formula: CH(-R300)=CH2 (V), and of formulae (VI) and (VII);    (2) varnish, which contains cyclic olefin copolymer and organic solvent;    (3) crosslinked component, which is obtained by crosslinking cyclic olefin copolymer; and    (4) molded product, which contains crosslinking component.    M=group 3-11 elements;    m=1-4;    R1-R6,X=H, halo, hydrocarbyl, heterocyclic compound residue, oxygen-containing group, nitrogen-containing group, boron-containing group, sulfur-containing group, phosphorus-containing group, silicon-containing group, germanium-containing group or tin-containing group;    adjacent R1-R6=ring;and    n=valence of M.