An optical modulator with CPW(coplanar waveguide) electode on Ti:LiNbO$_{3}$ optical waveguide wasfabricated and characterized. The electrical-optical bandwidth measurement showed an optical response of -3dBat 10 GHzand S$_{11}$ lessthan -10dB upto 20GHz. The typeical specifications are : 5.6V of driving voltage, 4.2dB of insertion loss and 30dB of on/off extinction. The eye pattern proved that the optical meduator, fabricated in this work, has properties good enough for application.