The present study analysed metacognition in the process of solving arithmetic word problem. Sixty-three fifth graders were divided into high and low performer groups based on their achievement of an arithmetic criterion test. The arithmetic word problem used in this study was made of five sub-stages: prediction of result, problem comprehension, planning, executing and evaluation of result. Two procedures were used in the present study. First came the workseat measuring problem solving behavior and the second consisted of a stimulated-recall interview to measure awareness concerning problem solving (metacognition). Verbal response and behavior in the problem solving and interview were recorded by VTR and tape-recorder. The main findings were as follows: (1) High performer had significantly more metacognition scores than low performer; (2) High performer showed more self -monitoring activity than the low one.