A copolymer for an electrode binder, which is a copolymer comprising: a structural unit (a) derived from a monomer represented by formula; a structural unit (b) derived from a monomer which is at least one kind selected from the group consisting of a (meth)acrylic acid and a salt thereof; a structural unit (c) derived from a monomer represented by formula; and a structural unit (d) derived from a hydrophilic monomer which is not any one of the monomer, the monomer or the monomer, has only one ethylenically unsaturated bond, and has an n-octanol/water partition coefficient LogP of less than 2.0, determined according to JIS Z 7260-117 as described in the description, and a structural unit (e) derived from a hydrophobic monomer which is not any one of the monomer, the monomer or the monomer, has only one ethylenically unsaturated bond, and has an n-octanol/water partition coefficient LogP of 2.0 or more; wherein: when a content of each component calculated by replacing the structural unit (b) contained in the copolymer with a structural unit derived from sodium acrylate is expressed as a converted content, a converted content of the structural unit (a) derived from the monomer is 0.5 % by mass or more and 20.0 % by mass or less; a converted content of the structural unit (c) derived from the monomer is 0.3 % by mass or more and 18.0 % by mass or less; a converted content of the structural unit (d) derived from the hydrophilic monomer is 0.5 % by mass or more and 15.0 % by mass or less; and a converted content of the structural unit (e) derived from the hydrophobic monomer is 2.5 % by mass or more and 20.0 % by mass or less, a converted content by combining the structural unit (c) derived from the monomer and the structural unit (d) derived from the hydrophilic monomer is 2.5 to 20.0 % by mass, wherein in the formula, R 1 and R 2 are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, wherein in the formula, R 3, R 4 and R 6 are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms; R 5 is an alkyl group having 1 to 5 carbon atoms, and has more carbon atoms than R 4; and n is an integer of 1 or more, m is an integer of 0 or more, and n + m ≥ 20. a structural unit (a) derived from a monomer represented by formula; a structural unit (b) derived from a monomer which is at least one kind selected from the group consisting of a (meth)acrylic acid and a salt thereof; a structural unit (c) derived from a monomer represented by formula; and a structural unit (d) derived from a hydrophilic monomer which is not any one of the monomer, the monomer or the monomer, has only one ethylenically unsaturated bond, and has an n-octanol/water partition coefficient LogP of less than 2.0, determined according to JIS Z 7260-117 as described in the description, and a structural unit (e) derived from a hydrophobic monomer which is not any one of the monomer, the monomer or the monomer, has only one ethylenically unsaturated bond, and has an n-octanol/water partition coefficient LogP of 2.0 or more; wherein: when a content of each component calculated by replacing the structural unit (b) contained in the copolymer with a structural unit derived from sodium acrylate is expressed as a converted content, a converted content of the structural unit (a) derived from the monomer is 0.5 % by mass or more and 20.0 % by mass or less; a converted content of the structural unit (c) derived from the monomer is 0.3 % by mass or more and 18.0 % by mass or less; a converted content of the structural unit (d) derived from the hydrophilic monomer is 0.5 % by mass or more and 15.0 % by mass or less; and a converted content of the structural unit (e) derived from the hydrophobic monomer is 2.5 % by mass or more and 20.0 % by mass or less, a converted content by combining the structural unit (c) derived from the monomer and the structural unit (d) derived from the hydrophilic monomer is 2.5 to 20.0 % by mass, wherein in the formula, R 1 and R 2 are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, wherein in the formula, R 3, R 4 and R 6 are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms; R 5 is an alkyl group having 1 to 5 carbon atoms, and has more carbon atoms than R 4; and n is an integer of 1 or more, m is an integer of 0 or more, and n + m ≥ 20. when a content of each component calculated by replacing the structural unit (b) contained in the copolymer with a structural unit derived from sodium acrylate is expressed as a converted content, a converted content of the structural unit (a) derived from the monomer is 0.5 % by mass or more and 20.0 % by mass or less; a converted content of the structural unit (c) derived from the monomer is 0.3 % by mass or more and 18.0 % by mass or less; a converted content of the structural unit (d) derived from the hydrophilic monomer is 0.5 % by mass or more and 15.0 % by mass or less; and a converted content of the structural unit (e) derived from the hydrophobic monomer is 2.5 % by mass or more and 20.0 % by mass or less, a converted content by combining the structural unit (c) derived from the monomer and the structural unit (d) derived from the hydrophilic monomer is 2.5 to 20.0 % by mass, wherein in the formula, R 1 and R 2 are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, wherein in the formula, R 3, R 4 and R 6 are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms; R 5 is an alkyl group having 1 to 5 carbon atoms, and has more carbon atoms than R 4; and n is an integer of 1 or more, m is an integer of 0 or more, and n + m ≥ 20.