To obtain a method and an apparatus capable of simultaneously separating a plurality of plastic moldings from a molding finished product formed with the plastic molding via a gate part to a plurality of runners extended radially from a sprue without using a cutter.

The method for simultaneously separating the plurality of the plastic moldings comprises the steps of contacting an annular end face of an ultrasonic oscillation horn with the plurality of the runners of the molding finished product at equally separating positions from a center of the sprue, giving an ultrasonic oscillation to give substantially uniform oscillations to the plastic molding including the gate to thereby break the weakest gate, and almost simultaneously separating all the moldings on the one molding finished product. The apparatus for simultaneously separating the plurality of the plastic moldings is provided.