In the Japan railway company group, the ultrasonic inspection is performed as a finished inspection for rails welded by aluminothermic and enclosed arc welding. The correctness of the ultrasonic inspection depends both on the ultrasonic detector and the probe in use. Therefore, we have newly developed a probe for rail welds to improve the correctness of ultrasonic inspection through the optimization of the crystal and wedge materials in the probe. Moreover, we propose a new specification of angle probe for the ultrasonic inspection of rail welds.