A coating device and a coating method capable of suppressing fluctuation in the width dimension of a coated film formed from an applied coating liquid, while having a discharge width that is easy to change. Specifically, the present invention is provided with: a slit nozzle (10) that has a discharge port (11) comprising a long widthwise slit (16) and that discharges a coating liquid from the discharge port (11) to coat a substrate (W); a drive unit (4) that moves the substrate (W) with respect to the slit nozzle (10) in a front-back direction; a discharge-width changing member (17) that changes the width dimension of the discharge port (11) by moving inside of the slit (16) in the widthwise direction; and an air-supply unit (21) that has an air nozzle (22) that sprays air on regions of both external widthwise sides of the coating liquid discharged from the discharge port (11), and which is capable of adjusting the spray location of the air from the air nozzle (22) corresponding to changes in the width dimension of the discharge port (11).
