Recently, learning with the portfolio assessment is paid attention to in Japan, because it focuses on the processes of children's learning. The portfolio assessment is one of the way of assessing children's activities and learning processes with their portfolios. The purpose of this study is to discuss the portfolio assessment on mathematical learning to develop the metacognitive ability. For the purpose of this study, this article proposed the framework of a rubric on mathematical learning with metacognitive perspectives. The rubric of portfolios refers to the scale of assessment of portfolios. Using this framework, you will be able to identify children's metacognitive activities, and use the portfolio assessment to develop the metacognitive ability. The characteristics of this framework are the followings; (1) it is two dimensions which are criteria and standards. (2) its criteria include four aspects. (3) its standards include the metacognitive aspects, and 5 levels. : Metacognition requires targets because of its definition (Flavell, 1976). So metacognitive aspects refer to its standers on this framework.