The present invention proposes a rotor/stator type mixer which is provided with a stator that is provided with a plurality of openings and a rotor disposed with a prescribed gap opened on the inside of the stator wherein said mixer can improve shearing stress applied to a fluid to be processed and exhibit higher performance and further said mixer can change and adjust the shearing stress applied to the fluid to be processed and change and adjust the manner in which the fluid to be processed flows. The rotor which is disposed with a prescribed gap opened on the inside of the stator which is provided with the plurality of openings is provided with a rotor peripheral wall that faces the inside of the stator peripheral wall where the prescribed gap is opened on the inside in the direction of the diameter of the peripheral wall of the stator in which the plurality of openings is formed and also a plurality of rotor openings are formed in the rotor peripheral wall.
