An apparatus which can remove particles, such as polishing debris, from a back surface with high removal efficiency is provided. The apparatus includes: a substrate holder configured to rotate the substrate while holding the substrate with the back surface facing upward; a scrub cleaning tool configured to be rotatable; a two-fluid nozzle disposed above the substrate holder; and a housing defining a cleaning chamber in which the substrate holder, the scrub cleaning tool, and the two-fluid nozzle are located.