Disclosed are a liquid processing apparatus and a liquid processing method that can prevent a substrate in a processing chamber from being contaminated due to contaminants attached to a nozzle supporting arm. The liquid processing apparatus includes a processing chamber in which a substrate holder holding a substrate and a cup disposed around the substrate holder are provided; a nozzle configured to supply a fluid to the substrate held by the substrate holder; and a nozzle supporting arm configured to support the nozzle. A gas ejection mechanism is installed at the nozzle supporting arm to eject a gas toward a front end surface of the nozzle supporting arm.