This paper intends to analyze the cause of performance assessment policy failure. The cause of policy failure is as follows. First, policy's realization possibility was not examined completely at the early stage of policy. And that policy have been practiced not voluntarily but defensively at the execution stage of policy. Secondly, that policy has been practiced depended on a teacher's sense of responsibility without the amendment of the education system and curriculum. It was not considered that the education tradition in Korean society such as the emphasis of quantitative and objective assessment, the disbelief of teacher's assessment ability, the abstract features of curriculum as a performance standards and the school as a educational organization for CSAT arrangement and so on will be influence on the policy. We have prepared the support system of teacher for a righteous practice of performance assessment policy. And It's also necessary to improve educational system.