Running gears such as bogie frame and wheelset are important components to ensure the safety of train operation. As their structure can not be fail-safe, they are fabricated carefully with a wide margin for safety. Regular inspections are also performed while they are in service to detect cracks and flaws without delay. This paper describes a strength evaluation method on welded joints of bogie frames, fracture mechanics evaluation on crack propagation on axles, and automatic ultrasonic testing devices developed for shinkansen vehicle axles.