Abstract: A primer composition may include an olefin-based resin (A), and a flaky pigment (B), and satisfy: (1) the primer composition contains a water-immiscible organic solvent, the pigment (B) has an average particle size of?25 ?m and is present in 17+wt. %, based on total primer composition solids; (2) the primer composition contains a water-immiscible organic solvent, the pigment (B) has an average particle size of<25 ?m is present in 42+wt. %, based on total primer composition solids, or (3): the primer composition contains water, the resin (A) is a water-based resin, and a pigment (B) content is 50 wt. % or higher based on total primer composition solids. Such a primer composition can be used in a primer coating film, a layered antifouling coating film, a method for producing a primer coated substrate, or a method for producing a layered antifouling coated substrate.