This paper presents a method for LiDAR sensor-based traversability analysis for autonomous mobile robots in urban environments. Although urban environments are structured environments, a typical terrain comprises hazardous regions for mobile robots. Therefore, a reliable method for detecting traversable regions is required to prevent robots from getting stuck in the middle of the road. Conventional approaches require considerable efforts to obtain a model for traversability analysis for a specific robot or environment. In particular, learning-based methods require explicit training data. This paper introduces a method for traversability mapping based on a self-training algorithm to eliminate the hand labeling process. A neural network was applied to the underlying classifier of the self-training algorithm. With our approach, the model can be learned with even weakly labeled data obtained from robot-specific parameters and the robot's footprint. In practical experiments, the self-trained model performed better performance than the existing supervised learning method. Moreover, as the fraction of unlabeled data increased, the performance also increased. Therefore, the demonstrations in the urban environments indicate the effectiveness of the proposed method for traversability mapping.