Substrate processing apparatus and substrate processing method

A substrate processing apparatus performs a chemical solution process in a chemical solution process room that is partially formed within a chamber. During the chemical solution process, the substrate processing apparatus seals the chemical solution process room, and measures the pressure within the chemical solution process room, and controls the pressure within the chemical solution process room, based on a measured value. Irrespective of location environment of the substrate processing apparatus, the chemical solution process room can be controlled to a predetermined pressure. The substrate processing apparatus also permits efficient pressure control with respect to a minimum required amount of region.