Disclosed are a substrate treating apparatus and a substrate treating method. The substrate treating apparatus including a spin head configured to support the substrate, a nozzle configured to discharge a chemical to the substrate located on the spin head, a first passage configured to supply a first chemical, a chemical property of which is the same as the chemical, a second passage configured to supply a second chemical, a chemical property of which is the same as the first chemical, and a discharge passage connecting the first passage and the second passage, and the nozzle.