A plasma apparatus includes a chuck disposed in a process chamber, a gas supply unit supplying a process gas into the process chamber, a plasma generating unit configured to generate plasma over the chuck, a direct current (DC) power generator applying a DC pulse signal to the chuck, and a sensor monitoring a state of the plasma and providing a sensing signal to the DC power generator. Each period of the DC pulse signal includes a negative pulse duration, a positive pulse duration, and a pulse-off duration. If a signal disturbance of the sensing signal occurs in an nth period of the DC pulse signal, the DC power generator changes a magnitude of a positive pulse and/or a length of the positive pulse duration of an n+1th period of the DC pulse signal, where “n” denotes a natural number.