TECHNOLOGY FOCUS - POLYMERS - Preferred Properties: The polymerization degree of styrene group repeating unit of formula (I), is 3 or more. The polymerization degree of repeating unit containing non-polar moiety, is 5 or more. The polymerization degree of repeating unit of formula (II), is 5 or more. The number average molecular weight of graft copolymer is 10000-5000000.Preferred Process: Block-copolymerization of repeating unit (I) and repeating unit having non-polar moiety, is carried out.Preferred Structure: The graft copolymer has blocks (B) and (C) having repeating unit comprising non-polar moiety, and block (A) having repeating unit (I), which are arranged sequentially as blocks (B-A-C). Preferred Composition: The number-of-moles of repeating unit of formula (I) is 0.001-50% with respect to total number-of-moles repeating units (I), (II) and repeating unit comprising non-polar moiety. The number-of-moles of repeating unit of formula (II) is 9.999-80% with respect to total number-of-moles of repeating units (I), (II) and repeating unit comprising non-polar moiety. The number-of-moles of repeating unit comprising non-polar moiety is 19.999-90% with respect to total number-of-moles of repeating units (I,II) and repeating unit comprising non-polar moiety. The repeating unit comprising non-polar moiety, is of formula (III), preferably repeating unit of formula (V).R7=hydrogen or optionally substituted 1-10C hydrocarbon;R8=optionally substituted hydrocarbon;andR11=hydrogen or methyl.The functional group having active halogen atom contained in styrene compound (VI) used for manufacture of graft copolymer, is a group of formula CR19R110 (IX).R9,R10=hydrogen, halogen or optionally substituted hydrocarbon.Preferred Initiator: The stable radical type initiator used for manufacturing graft copolymer, is stable free radical compound (such as nitroxyl compound), radical polymerization initiator (such as organic peroxide or azo compound) or alkoxy amine.Preferred Electrolyte Salt: The electrolyte salt contained in the solid polymer electrolyte is quaternary-ammonium salt, quaternary-phosphonium salt, transition-metal salt and/or alkali-metal salt (preferably, lithium salt). Preferred Definitions:    R2=functional group of formula CR9R10 (IV); and    R9=hydrogen, halogen or optionally substituted 1-10C hydrocarbon.    EXAMPLE - 4-chloromethyl styrene (in mmol) (131) and 1-(2,2,6,6-tetramethylpiperidinyloxy)-1-phenylethane (9.6) were uniformly mixed. The mixture was subjected to nitrogen bubbling for 15 minutes, and polymerized at 125 degrees C in nitrogen atmosphere. After 12 hours, the reaction solution was cooled to 0 degrees C, and polymerization was terminated. The reaction solution was diluted with tetrahydrofuran, to obtain a homogenous solution. The obtained homogenous solution was supplied to methanol, and polymer was precipitated. The precipitated polymer was filtered, washed and dried under reduced pressure. The yield of obtained polymer was 56%. The obtained polymer had number average molecular weight (Mn) of 1300, and weight average molecular weight (Mw)/(Mn) of 1.35. The obtained polymer (0.7) was mixed with styrene (400), and polymerized under nitrogen atmosphere. The obtained reaction solution was diluted by tetrahydrofuran, and the polymer was precipitated by adding methanol. The obtained polymer was filtered, washed and dried under reduced pressure, to obtain block copolymer having Mn of 37000 and PD of 1.48. The obtained block copolymer (0.1), methoxy polyethylene glycol monomethacrylate (38), cuprous chloride (0.1), and 2,2'-bipyridine (0.2) were mixed and co-polymerized. After 20 hours, the reaction solution was cooled to 0 degrees C, and unreacted monomer and metal complex were removed. The volatile content of the obtained block-graft copolymer were removed under reduced pressure. The obtained copolymer had Mn of 310000 and PD of 1.52. The number-of-moles of repeating units such as 4-chloromethyl styrene repeating unit, styrene repeating unit, and polyethylene glycol monomethacrylate repeating unit in the obtained copolymer were found to be 1.2%, 56.8% and 42%, respectively. The obtained copolymer was dissolved in acetone, under argon atmosphere. Then, lithium perchlorate (0.2 g) was added and dissolved, to obtain a resin composition. The obtained resin composition was applied on Teflon board, and dried to obtain solid-polymer-electrolyte film of 100 microns thickness. The obtained film was inserted into platinum board, and ionic conductivity was measured by a complex-impedance analysis using impedance analyzer, and found to be 5 x 10-4 S/cm at 23 degrees C.