PURPOSE: To acquire a treatment device which can prevent contamination of a treatment object by supplying treatment solution uniformly to a surface of the treatment object.

CONSTITUTION: In a treatment device provided with a spin chuck 20 for holding a semiconductor wafer W horizontal which is a treatment object and a treatment solution supply nozzle 21 wherein a plurality of nozzle holes 22 for discharging treatment solution are provided in line on a surface of the semiconductor wafer W, the semiconductor wafer W and the treatment solution supply nozzle 21 are formed to enable relative horizontal movement. An area of the nozzle hole 22 is increased gradually by gradually narrowing a pitch of the nozzle hole 22 from a center part of the treatment solution supply nozzle 21 toward an outside thereof or by gradually increasing an aperture of the nozzle hole 22. Thereby, treatment solution is supplied uniformly to a surface of the semiconductor wafer W.