Provided are a substrate treating unit, and substrate treating apparatus and method using the same. Two nozzle arms are provided, and photoresist liquid nozzles and an organic solvent nozzle are installed in each of the nozzle arms. A temperature of a photoresist liquid flowing into the photoresist liquid nozzles and a temperature of an organic solvent flowing into the organic solvent nozzle are maintained by a temperature control fluid supplied through the same passage. Also, a waiting port in which a nozzle arm used in a process temporarily waits is provided. The organic solvent is provided to a photoresist liquid nozzle that is not used in a process and is not provided to a photoresist liquid nozzle used in the process.