A plasma processing apparatus includes a chamber defining a process space, an upper electrode mounted in the chamber, the upper electrode including a first gas spray port located in a central region of the upper electrode and a second gas spray port located in a peripheral region of the upper electrode, a lower electrode located opposite the upper electrode across the process space, a first gas supply unit configured to supply a first process gas into the process space via the first gas spray port and the second gas spray port, a second gas supply unit configured to supply a second process gas into the process space via the second gas spray port, a sensor configured to sense a state of plasma in an edge portion of the process space, and a controller configured to control the second gas supply unit in response to an output signal of the sensor.