The fracture morphologies of mud pastes show significantly complex patterns in nature. The mud pastes initially have fluid-like properties, but gradually change from "fluid" to porous "solid" in their drying process. The mudcrack phenomena in nature, therefore, is one of the complex physical phenomena of interest in material sciences. However, although it has been considered that mudcracks may be induced by the friction caused by the differences between shrinkage ratios of soil skeletons, the mechanical details remain unknown. In this work, we attempt to develop a novel numerical model based on three dimensional finite element method for mudcrack growth in Bentonite pastes. This model is the first description for mudcrack simulation based on three dimensional solid analysis. In order to validate the proposed model, Hausdorff fractal dimension of the numerical fracture patterns is compared with those of the experiments. As a result, the numerical results showed fracture patterns reasonably, and the fractal dimension of the cracking pattern by numerical simulation was almost consistent with the experimental results.