A model for fracture of ceramics has been proposed. Based on the model, an evaluation method of fracture strength for ceramics has been developed. It is well known that fracture strength for ceramics has a large scatter because of included defects. Generally it is thought that the scatter of fracture strength depends on the defect size alone. However, we experience that fracture toughness has a scatter even if it is measured by the IF method. The crack introduced by the IF method is very small; thus, it cannot be considered that defects are included in the crack surface. Therefore we have established a model for fracture of ceramics by introducing the probability distribution of fracture toughness. Fracture probability for an arbitrarily shaped specimen can be evaluated by using this model.