Provided is a binder composition that can produce a slurry composition having excellent preservation stability and that can cause a functional layer to display excellent adhesiveness. The binder composition contains a polymer and a solvent. The polymer includes a (meth)acrylic acid ester monomer unit including an aromatic hydrocarbon ring in a proportion of not less than 5 mass % and not more than 45 mass % and includes a structural unit indicated by formula (I), shown below, in a proportion of not less than 50 mass % and not more than 90 mass %. In formula (I), R1 represents a hydrocarbon group having a carbon number of 4 or more that does not include an aromatic hydrocarbon ring and R2 represents a hydrogen atom, a methyl group, or —CH2—C(═O)—O—R1. In a case in which more than one 10 is present in formula (I), each R1 may be the same or different.