Disclosed is a coating apparatus configured to properly detect a liquid surface of a coating liquid stored within a slit nozzle. The disclosed coating apparatus includes a slit nozzle, a moving mechanism, a storage portion illumination unit, and an imaging unit. The slit nozzle includes an elongated main body, a storage portion configured to store a coating liquid within the main body, and a slit-shaped ejecting port configured to eject the coating liquid fed from the storage portion through a slit-shaped flow path, wherein at least a part of each of a first wall and a second wall which face each other in the main body is formed of a transparent member. The moving mechanism is configured to move the slit nozzle with respect to a substrate. The storage portion illumination unit is configured to illuminate an inside of the storage portion through the transparent member of the first wall. The imaging unit is configured to image the inside of the storage portion through the transparent member of the second wall.