A coating apparatus is known in which a coating liquid is continuously delivered from the front-end slit of a die nozzle for application onto a base film which constantly runs without being supported from the back. The improvement is made in which the die nozzle has at the film loading side a front lip and at the film unloading side a rear lip provided at least with a convex surface, both of which being arranged in step relationship so that the slit side end of the front lip is set back from the path of the base film to locate lower than that of the rear lip. Thereby, a higher shear force will be exerted on the magnetic coating liquid temporarily trapped in a space defined by the running base film and the slit side end of the rear lip, thus allowing a smooth surfaced coating to be developed of a highly agglomerative coating material.