NOVELTY - A collector contains resin layer having electroconductivity. The resin layer contains copolymer formed by polymerizing monomer containing olefin type monomer (I) and hydroxyl-group containing ethylenically unsaturated monomer (II) as a base material, where the repeat unit number derived from the olefin type monomer is 25-50 mole% with respect to all the repeat unit numbers, and the repeat unit number derived from the hydroxyl-group containing ethylenically unsaturated monomer is 50-75 mole% with respect to all the repeat unit numbers.    USE - Collector for a bipolar secondary battery (claimed) such as lithium ion battery and nickel-hydrogen battery, which is utilized for hybrid electric vehicle and electric vehicle.    ADVANTAGE - The collector improves cyclic characteristics, charging/discharging capacity, energy density and durability of the battery, and suppresses a molecular motion of the copolymer, thus effectively eliminating the swelling of the resin collector by a solvent.    DETAILED DESCRIPTION - A collector contains resin layer having electroconductivity. The resin layer contains copolymer formed by polymerizing monomer containing olefin type monomer of formula ((R1)2C=C(R1)2) (I) and hydroxyl-group containing ethylenically unsaturated monomer of formula ((R2)2C=C(R2)(A-OH)) (II) as a base material, where the repeat unit number derived from the olefin type monomer is 25-50 mole% with respect to all the repeat unit numbers, and the repeat unit number derived from the hydroxyl-group containing ethylenically unsaturated monomer is 50-75 mole% with respect to all the repeat unit numbers.    R1,R2=H or 1-4C alkyl;and    A=single bond or 1-4C alkylene.    An INDEPENDENT CLAIM is also included for a bipolar secondary battery comprising a collector, a positive electrode active material layer or negative electrode active material layer formed on a surface of the collector, and an electrolyte layer containing carbonate-type solvent.    DESCRIPTION OF DRAWING(S) - The drawing shows a sectional view of a bipolar secondary battery.    Bipolar secondary battery (10)    Collector (11)    Outermost layer collector of positive electrode side (11a)    Outermost layer collector of negative electrode side (11b)    Positive electrode active material layer (13)    Negative electrode active material layer (15)