We investigated crack propagation in the drying process of a thin layer of calcium carbonate (CaCO 3 ) paste experimentally. Cracks are induced by uniform desiccation from the top surface of a layer at the approximately same water content for various drying conditions. We found that the crack speed is a nonlinear increasing function of the drying rate at the cracking time although the tensile stresses arising in the bulk of paste do not depend practically on the drying rate. The crack speed does not depend significantly on the layer thickness and decreases in the cases in which glycerol is mixed to increase the viscosity of paste. These results suggest that dynamical crack growth occurs with viscoplastic relaxation in the vicinity of crack tips.