A plasma process monitoring device capable of monitoring plasma light distributed in a certain area in a chamber includes a selection area light transmitter and a monitor. The selection area light transmitter is disposed to face a viewport formed in a chamber and includes a plurality of selective light blockers for selectively blocking plasma light emitted through the viewport. The monitor receives plasma light transmitted through at least one of a plurality of selective light blockers to acquire information on the plasma light, and monitors the uniformity of plasma generated in the chamber based on the information on the plasma light.