This research work focused on checking the cause and evaluation of cracks at every stage in R.C.C structures. This paper will describe how to find out cracks size and cause of cracks. Cracks generally occur both in plastic and elastic state of concrete. I have selected this topic because less work is being done in this area in India. The repair materials and repair technique are different depending upon forms of cracks according to their positions in structure. Good crack repair methods depends on knowing the cause of cracks and selecting appropriate repair method that take these causes into account otherwise the repair would not last long. This report serves as a tool in process of cracks evaluation and causes of cracks in concrete structures. So we can say if crack repair is assumed to be building of structure than this report can be assumed as foundation of it.