We designed the cutter profile for symmetric screw rotor and did vibration experiment of screw rotor manufactured by the designed cutter profile. The results of this study are summarized as follows. (1) We designed the cutter profile of screw rotor (4-6)(5-6) by using numerical analysis program. (2) The maximum amplitude and variation of amplitude of 5-6 profile rotor are about 30 - 36.7% and 10 - 25% smaller than those of 4-6 profile rotor, respectively. (3) As the angular velocity of rotor changes from 100 to 300 rpm, the vibration of X, Y axis in driving shaft of 5-6 profile rotor is about 10 - 20% smaller than that of 4-6 profile rotor.