In this work it is simulated the random telegraph noise signal amplitude dependence on gate voltage overdrive for silicon on insulator junctionless FinFET transistor with fin cross section in rectangle and trapeze form. It is shown in subthreshold region the noise signal amplitude is lower in case of trapeze cross section of the fin. Besides it approximately at the same condition the noise signal amplitude is essentially lower in junctionless fin field effect transistor than in bulk, fully depleted silicon on insulator and ordinary fin field effect transistors.