[en] In order to ensure the reliability and safety of nuclear power plants and stably supply electric power, the regular inspection of once every year is obligated by the law, and mainly the confirmation of the soundness of machinery and equipment is carried out by nondestructive inspection techniques. Since these inspections are made frequently in radiation environment, various automatic inspection devices have been developed and practically used, which contribute to the reduction of dose equivalent of inspectors, the shortening of working time and the improvement of the reproducibility of inspection results. In this report, the automatic ultrasonic flaw detection apparatus used for the welded parts of pipings is described. The problems in the ultrasonic flaw detection by manual operation and the requirement when the automatic ultrasonic flaw detection apparatus for pipings was developed are described. The apparatuses for straight pipes and curved pipes and the multiple joint manipulator type apparatus are explained. (K.I.)