This paper presents the wind tunnel test results for measuring aeroacoustic noises originating from several half-size models of a louver used at an air intake hole, which is often seen on the side plate of the rolling stock of a Japanese high-speed train. Based on the acoustic characteristics of the measured sounds radiating from the louver when an airflow passes by, the following conclusions are reached. (1) Aeroacoustic sounds radiating windward and leeward from a louver of standard type are significant, possibly caused by pressure fluctuation on the strips reinforcing the louver, which are fixed crosswise to partitioning strips and usually to an airflow. (2) Recommended countermeasures for strong and dipolelike sounds originating from the reinforcing strips are reducing the number of the strips, adopting a roundish shape like an ellipse for their cross sections, and fixing them somewhat inside, avoiding windy positions. (3) It is ascertained that rounding the right-angled edges, which are located windward and leeward, of the framework of an air intake opening has considerably desirable effects on both generated sounds and the capacity of the air intake.