In this 5th report “Ditch-type” and “Stiffener-type” arresters are considered. In the former the arresting of brittle crack is effected by the mechanical factor associated with the singularities of stress field due to “ditch way” where discontinuous change in plate thickness exists and as well as to the increase in toughness of the material by plate thickness reduction. The latter type is similar to stiffener and frame which are popularly seen in the plate and shell structures. In the case of stiffener type arrester, material quality and/or dimensions of stiffener is so tough that the stiffener never breaks even when the crack in plate passes the line where the stiffener is attached and the crack arresting is effected by the crack closing action of the stiffener. Stress intensity factors with the presence of the above two types of arrester are approximately calculated and the results are compared with those of brittle crack propagation-arrest test using the double tension specimens with arresters. In connection with the analysis of Ditch-type arrester, the mechanical effect of plate thickness on fracture toughness is discussed. Further it has been found out that the stiffener type crack arrester is effective and promising from the practical point of view.