The present invention provides a resist coating and developing apparatus, a resist coating and developing method, a resist-film processing apparatus, and a resist-film processing method, capable of reducing a line width roughness by planarizing a resist pattern. The resist coating and developing apparatus comprises: a resist-film forming part configured to coat a resist onto a substrate to form a resist film thereon; a resist developing part configured to develop the exposed resist film to obtain a patterned resist film; and a solvent-gas supply part configured to expose the resist film, which has been developed and patterned by the resist developing part, to a first solvent of a gaseous atmosphere having a solubility to the resist film. A solvent supply part supplies, to the resist film which has been exposed to the first solvent, a second solvent in a liquid state having a solubility to the resist film.