This article determines the provision of scaffolding on students' metacognitive failure in solving mathematical problems. Students' metacognitive failure in solving mathematical problems may be simplified into three levels of scaffolding: (1) environmental provisions, (2) explaining, reviewing and restructuring and (3) developing conceptual thinking. This qualitative research had 15 students as prospective research subjects and were divided into two groups: those who half-finished the task, and the others who finished the task completely, though both groups were resulting wrong answer. From each group, a research subject was taken. Data were collected as the subject did the task with think-aloud method, then the subject was interviewed based on his work. This study found that the metacognitive failure occurred thrice in those who half-finished the task, and scaffolding level 1 was given. On the contrary, metacognitive failure in another group was occurred 5 times, and scaffolding level 1 and 2 were given.