Abstract: A plasma processing apparatus includes a process chamber including an inner space; an electrostatic chuck on which a substrate is loaded in the process chamber; a side-gas injection unit that is installed above the electrostatic chuck and includes at least one gas nozzle having an inclined gas flow path that is inclined with respect to a nozzle axis to obliquely supply a process gas into the process chamber from a sidewall of the process chamber; a plasma generation unit configured to generate plasma from the process gas injected into the process chamber; and a controller configured to control the electrostatic chuck, the side-gas injection unit, and the plasma generation unit. The controller controls process parameters under a cyclic ramping condition in which a cycle of the process parameters is continuously increased or decreased.