Desiccation cracking is a phenomenon in which cracks are caused by shrinkage of drying paste material. In the present study, digital image correlation, DIC, is applied to measure the displacement field at the crack tip in a drying paste. In order to obtain magnified images around the crack tip, the control method for crack nucleation position and crack propagation direction is newly developed. Furthermore, stress intensity factors are evaluated by iterative procedure from the measured displacement field. The results show that the stress intensity factors are varied during crack propagation because of kinked crack path ant the fracture toughness depends on the paste thickness even the paste is composed of the same powder. In addition, it is found that the fracture toughness is independent of the crack propagation speed. The dependence of the fracture toughness on the paste thickness is noticeable results to analyze the fracture of desiccation cracking.