A coating device configured to apply a coating liquid to both surfaces of a substrate that has a sheet shape and is transported. The coating device includes: a pair of blocks facing each other in a thickness direction of the substrate; and a liquid reservoir that is formed such that the coating liquid is accumulated in a gap between the pair of blocks, and through which the substrate passes, wherein the liquid reservoir includes: an introduction port that is opened on an upstream side in a transport direction of the substrate and through which the substrate is introduced, a discharge port that is opened on a downstream side in the transport direction and through which the substrate is discharged, and side surface portions respectively positioned on both sides in a width direction intersecting the transport direction, at least a side surface portion on one side of the both sides in the width direction among the side surface portions has an exposure port that is opened from the introduction port to the discharge port, and a part of the substrate in the width direction is configured to protrude from the exposure port to an outside of the liquid reservoir.