In the present invention, a substrate transfer unit into/from which a substrate is transferred from/to the outside of a treatment container and a developing treatment unit in which development of the substrate is performed are arranged side by side in the treatment container, and a carrier mechanism is provided which carries the substrate while grasping an outside surface of the substrate from both sides, between the substrate transfer unit and the developing treatment unit. A developing solution supply nozzle for supplying a developing solution onto the substrate and a gas blow nozzle for blowing a gas to the substrate, are provided between the substrate transfer unit and the developing treatment unit and above a carriage path along which the substrate is carried, and a cleaning solution supply nozzle is provided in the developing treatment unit for supplying a cleaning solution onto the substrate. According to the present invention, since the substrate is carried with its outside surface being grasped, spread of contamination can be prevented to restrain generation of particles in the treatment container.