JunjiUrakawa1-TheUniversityofTokyo-DepartmentofPhysics7-3-1Hongo,Bunkyo-ku,Tokyo113-0033-Japan2-TheUniversityofTokyo-ICEPP7-3-1Hongo,Bunkyo-ku,Tokyo113-0033-Japan3-KEK-AcceleratorLaboratry1-1Oho,Tsukuba,Ibaraki305-0801-Japan4-KEK-InstituteofParticleandNuclearScience1-1Oho,Tsukuba,Ibaraki305-0801-JapanThe beam test for the Shintake monitor succeeded in measuring signal modulationwiththelaserinterferencefringepatterninNovember2009. Wehavestudiedtheerrorsources, and evaluated the systematic error to be less than 30% for 1 minute mea-surements. ThispapercentersontheevaluationoftheShintakemonitorperformancethroughanalyzingbeamtestsdeta. Mostsystematicerrorsourcesarewellunderstood,enablingaccuratemeasurementofthebeamsizewhenitreaches37nm.