To provide a substrate-treating device for supplying the rectification of clean air including ions for destaticizing to a substrate.

A fan filter unit 50 having destaticizing functions has a configuration, where an ionizer 524 is arranged so that a region in which the air current of clean air passes immediately above a blasthole 523 is surrounded, thus preventing the air current of clean air toward the blasthole 523 from being disturbed by the ionizer 524, and supplying the down flow of clean air containing ions from the blasthole 523 to a robot arrangement space 22 in the state of rectification. As a result, when a wafer W carried by an indexer robot IR passes through the robot arrangement space 22, ions are supplied to the surface of the wafer W, and the static electricity is neutralized by ions for removal when the wafer W is electrified by static electricity.