Patent attributes
A substrate liquid processing apparatus includes a processing liquid storage unit configured to store a processing liquid therein; a processing liquid drain unit configured to drain the processing liquid from the processing liquid storage unit; and a control unit. The control unit performs a first control in a constant concentration mode in which a concentration of the processing liquid in the processing liquid storage unit is regulated to a predetermined set concentration and a second control in a concentration changing mode in which the concentration of the processing liquid is changed. In the second control, a set concentration after concentration change is compared with a set concentration before the concentration change, and when the set concentration after the concentration change is lower, the control unit controls the processing liquid drain unit to start draining of the processing liquid.
