Disclosed is a substrate treating apparatus. All treating units are each arranged such that a treatment chamber, a chemical piping space, and an exhaust chamber are located side by side along a transportation space, the chemical piping space is located on a first side of the treatment chamber, and the exhaust chamber faces the chemical piping space across the treatment chamber when seen from the transportation space. The exhaust chamber faces the chemical piping space across the treatment chamber, leading to prevention of obstruction of a passage for passing a pipe, configured to supply a chemical to a substrate held by a holding rotator, by an exhaust pipe. Moreover, a single type of treating units is enough for the substrate treating apparatus instead of two types of treating units currently used. This results in sharing of components by all the treating units.