Provided are a binder aqueous solution for a lithium-ion battery electrode, a slurry for a lithium-ion battery negative electrode, a negative electrode for a lithium-ion battery, and a lithium-ion battery. The binder aqueous solution for a lithium-ion battery electrode contains an acidic group-containing water-soluble polymer (A) and an amino group-containing water-soluble polymer (B). The acidic group-containing water-soluble polymer (A) is a polymer of a monomer group containing, with respect to 100 mol % of the monomer group, 30 mol % to 90 mol % of a (meth)acrylamide group-containing compound (a), 3 mol % to 20 mol % of an unsaturated organic acid (b), and 5 mol % to 40 mol % of an alkali metal or alkaline earth metal salt (c) of the unsaturated organic acid. A 1% by mass aqueous solution of the amino group-containing water-soluble polymer (B) has a pH of 9 or higher.