Provided is a method and apparatus for treating a substrate with a liquid. The substrate treating method comprises a pre-treating step for supplying the treatment liquid containing hydrogen fluoride (HF) to the substrate and treating the substrate before the surface modification step and a surface modification step for supplying an alkene-based chemical onto a substrate to change the surface of the substrate to a hydrophobic state. As a result, the surface of the substrate is uniform, and generation of particles can be reduced when the substrate is removed.