TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Component: The dispersion medium is chosen from alcohol compound solvent, amide compound solvent, ketone compound solvent, ether compound solvent, aromatic compound solvent, aliphatic compound solvent, and nitrile compound solvent.    TECHNOLOGY FOCUS - POLYMERS - Preferred Composition: The high-molecular compound contains cyclic structure-containing structural unit of formula: -(-C(-W1)(-Z11)(-W3)(-Z13)-C(-W2)(-Z12)(-W4)(-Z14)-)- (I) or -(-C(-Z21)(-Z23)-C=C-C(-Z22)(-Z24)-)- (II), structural unit derived from macromonomer (X) having weight average molecular weight of 1000 or more, and/or repeating unit derived from a monomer chosen from (meth)acrylic acid monomer, (meth)acrylate monomer, and (meth)acrylonitrile monomer. The high-molecular compound contains a functional group (b) chosen from carbonyl group, amino group, carboxyl group, sulfonic acid group, phosphoric acid group, phosphonic acid group, hydroxyl group, oxy group, cyano group, sulfide group, and imino group, and a functional group (c) chosen from carboxyl group, sulfonic acid group, phosphoric acid group, and hydroxyl group. The macromonomer (X) contains polymerizable double bond and 6C or more linear hydrocarbon structure unit. The macromonomer (X) is a monomer containing carbonyl group-containing repeating unit of formula: (H2C=C(-Rb2)-C(=O)-O)na-R'a (III), (H2C=C(-Rb2)-C(=O)-N(-R'n)-)na-R'a (IV), (V) or (VI), or aryl group-containing repeating unit of formula (VII) or (VIII). The composite solid electrolyte composition further contains an active material capable of performing insertion discharge of metal ions of group-1 or group-2 elements of periodic table. The content of binder particles in the composite solid electrolyte composition is 0.1-20 parts mass with respect to 100 parts mass inorganic solid electrolyte. The content of shell portion in the binder is 5-200 parts mass with respect to 100 parts mass core portion.W1-W4=single bond or divalent connecting group;Z11-Z14,Z21-Z24=H or substituent, at least one being substituent;or 2 or more of W1-W4,Z11-Z14,Z21-Z24=cyclic structure;Rb2,Rb3=H, halo, hydroxy, cyano, alkyl, alkenyl, alkynyl, or aryl;na=1-6;R'a,R'b=coupling group;or R'a=monovalent substituent (when na is 1);andR'n=H, 1-6C alkyl, or 6-10C aryl.Preferred Properties: The core-shell-type particles have an average particle diameter of 10-1000 nm, preferably 200 nm or less. The glass transition temperature of core portion is higher than the glass transition temperature of shell portion, or the glass transition temperature of shell portion is higher than the glass transition temperature of core portion. The glass transition temperature of core portion or shell portion is 80 degrees C or more or 30 degrees C or less.