An inkjet printer includes an image-forming part, forming an auxiliary layer on a base material by ejecting droplets of auxiliary ink and forming an image on the auxiliary layer by ejecting droplets of image-forming ink, the auxiliary ink changing a dot formation state of droplets of the image-forming ink. In a storage part, a reference table that associates each of a plurality of types of base materials with a proper dot area rate to be used when forming the auxiliary layer is stored. In a dot-area-rate determination part, a dot area rate to be used when forming the auxiliary layer on a target base material is determined as an auxiliary ink dot area rate by referencing the reference table using the type of the target base material. This enables the inkjet printer to form a highly precise image on various base materials.