A method of producing particles by bringing plural dissimilar materials A and B into contact with each other includes feeding a liquid into a reactor from a first end portion of the reactor such that the liquid flows along the inner peripheral surface of the reactor and generating a vortex flow toward a second end portion in the reactor by the feed of the liquid; disposing a flow-assisting blade capable of rotating around the central axis line in the reactor and rotating the flow-assisting blade; and injecting materials to be contacted A and B into the reactor, discharging a contacted liquid from the second end portion of the reactor, and generating the particles in the contacted liquid.