Old railroad tracks often cause problems such as broken rails, worn rails, or stretched rails. This is because the steel rails are prone to deformation when the train is operating, rails receive heavy loads. If it is allowed to continue this can be dangerous and cause train accidents. Therefore, periodic maintenance is needed to minimize it. The material surface change detector is a tool for detecting changes in the railroad material plane. This tool is based on the Arduino Mega microcontroller and an ultrasonic sensor as a measuring tool. Sensor input data is managed on the Arduino microcontroller and stored in the form of text data on the Micro SD Card. Testing the instrument for detecting changes in the surface of the material is carried out statically and dynamically by using two specimens with different thickness variations. In dynamic testing, the material surface change detector will test at a speed of 0.5 and 1 km/h. The static and dynamic test data analyzed is used to determine the character of the sensor and the effectiveness value of the sensor used for testing the thickness of the rail. The development of the results of this study is intended for further research in the field of rail testing equipment, with the addition of more complex test parameters, to produce data and testing tools that are optimal for field conditions.