There is provided a primer composition capable of effectively enhancing
anti-plasticizer property and water resistance even without curing of the
primer layer, and a bonded structure. A primer composition forms a primer
layer, containing a polymer, of a paint film formed by painting and
drying on a surface to be painted; and a bonded structure includes: a
base material, a primer layer containing a polymer sticking fast to the
base material, and an adhesive sheet having an adhesive layer stuck fast
to the primer layer. The polymer contains a polycarbonate polyurethane
having a repeated unit derived from polycarbonate polyol in a molecule
thereof.