The authors performed laboratory experiments and field measurements to investigate low-frequency noise generated in wayside environments from high-speed train running. The results indicated the following three types of low-frequency sound sources: pressure fields around the nose and tail parts of the train, low-frequency acoustic pressure waves aerodynamically caused by the train itself, and noise radiation from vibrating concrete railway viaducts. Measurements conducted in a higher-speed section revealed that the major sound source of low-frequency noise in the far field was aerodynamically generated unsteady flow, which is analogous to a line source.