NOVELTY - An ionically conductive composition comprises a linear copolymer obtained by polymerizing a compound (A) with 2 functional groups (a) and a compound (B) having 2 functional groups (b), and an electrolyte. It has lightweight, flexibility, transparency and film-forming properties.    USE - The conductive compositions are useful for cells (claimed) e.g. solar cells.    ADVANTAGE - Such compositions contain block copolymers with functional groups particularly for producing network structures.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: (i) A composition comprising a linear copolymer prepared from (A) and (B) wherein the copolymer with functional groups (b) at its both ends is further reacted with a compound (D) having not less than 3 functional groups (a), and electrolyte; (ii) a composition comprising a polymer obtained by the reaction of a compound of formula (B-1) and a compound of formula (D-1), and an electrolyte;        R1 = (un)substituted 1-18C alkyl, 7-21C aralkyl, or (un)substituted 6-20C aryl;    n1 = 0-500.        R31 = H, (un)substituted 1-18C alkyl, or (un)substituted 6-20C aryl;    R32 = 1-18C alkylene, 7-21C arylalkylene, 1-12C heteroatom-containing alkylene with 1-6 heteroatoms, or direct bond;    n31 = not less than 3; and    Z3 = a linking group with a valency number same as the value of n31 including C, Si, monosubstituted trivalent Si, 1-30C aliphatic group, 1-30C heteroatom-containing organic group with 1-6 heteroatoms, benzenecarboxyl group, phosphate group, or 2-50 Si linear, branched or cyclic alkyl siloxane group.    (iii) another similar composition comprising a copolymer prepared by reacting a linear polymer of (A) and (B) with a compound (E) with not less than 3 functional groups (b) in the presence of (A) and/or (B), and an electrolyte; (iv) a cell made by applying a monomer component in the conductive composition onto the positive and negative electrodes before polymerization; or by impregnating a support in the monomer component-containing conductive composition prior to polymerization and fixing the positive and negative electrodes on; or by filling the monomer component-containing conductive composition into the cell before polymerization; or by impregnating a support before fixing the positive and negative electrodes on and polymerization; (v) a gel-type composition containing a crosslinked copolymer obtained by the reaction of a linear copolymer made from compounds of formula (A-1) and (B-1) or dimethylsilane, with a compound of formula (D-1), or of (E-1), and solvent;        R21 = (un)substituted 1-18C alkyl, 1-18C aralkyl, (un)substituted 6-20C aryl;    R22 = 1-8C alkylene, (un)substituted 6-20C arylene    7-21C arylalkylene, or direct bond;    Z2 = divalent group.        R21 = H, (un)substituted 1-18C alkyl, or (un)substituted 6-20C aryl;    R52, R53 = independently H, (un)substituted 1-18C alkyl, 7-21C aralkyl, or (un)substituted 6-20C aryl;    n51, n52 = not less than 0;    R52 and R53 can be linked together through -O-, and provided that the total number of Si directly bonded to H is not less than 3 when R52 and/or R53 is H.    (vi) a similar gel-type composition containing a crosslinked copolymer obtained by reacting compounds of formula (D-1), (E-1) and (F);        R41 = H, (un)substituted 6-20C aryl;    R42 = 1-18C alkylene, (un)substituted 6-20C arylene, 7-21C arylalkylene, or direct bond;    R43 = H, (un)substituted 1-18C alkyl, or (un)substituted 6-20C aryl;    A2 = divalent group;    (vii) a gel-type composition containing a crosslinked copolymer obtained by reacting a modified polysiloxane compound with not less than 2 hydrosilyl groups made from (A-1), (E-1) and (F), or from (B-1), (E-1) and (F), with (D-1), and solvent.