The present invention provides a plasma generating system that includes: a waveguide for transmitting a microwave energy therethrough; an inner wall disposed within the waveguide to define a plasma cavity, wherein a plasma is generated within the plasma cavity using the microwave energy; a first gas inlet mounted on a first side of the waveguide and configured to introduce a first gas into the plasma cavity and generate a first vortex flow within the plasma cavity using the first gas, the first gas inlet having a through hole through which a gas processed by the plasma exits the plasma cavity; and a plasma stabilizer having a shape of a circular hollow cylinder and installed on a second side of the waveguide, an axial direction of the plasma stabilizer being in parallel to a rotational axis of the first vortex flow.