An apparatus for cutting pipes made of plastic material in automatic cutter machines, including a tool for cutting pipes made of plastic material, a first rocker arm supporting the cutting tool, movable between a non-operating configuration at which the tool is disengaged from the pipe and an operating configuration wherein the tool is designed to exert its cutting action on the pipe, a second arm, for controlling the first arm, operatively connected to the first arm for moving it at least between its non-operating and operating configurations, the second arm comprising a first electric actuator and a supporting body slidably connected for modifying its reciprocal position between a close position and a spaced-apart position.