Growing traffic congestion has made intelligent transport systems (ITS) vital for a safer and more efficient automobile society. In this system, the classification of the moving vehicle on the road is the key function, and vehicle detection and axle counting are especially important for the enhancement of this classification.1–5 The line scanning time-of-flight (TOF) laser sensor is an attractive tool for this detection and counting. This sensor can capture the cross section of a vehicle by laser beam scanning from the side of the road and obtain a three-dimensional (3-D) shape when the vehicle crosses the laser scanning section. This 3-D shape information is very useful for enhancement of the vehicle detection and axle counting. For the laser sensor in this application, there are three qualitative requirements: (i) large receiving aperture to realize high signal-to-noise ratio (SNR), (ii) wide field-of-view (FOV) to cover the detection area, and (iii) high scanning speed to realize enough spatial resolution for both scanning and vehicle moving directions. In the past, there were some scanning laser sensors used for this application, and they used coaxial optics and a polygon scanner. For this configuration, a large polygon scanner must have a large receiving aperture and obtain a high SNR. Consequently, the scanning speed must be low owing to this large scanner. For example, the scanning speed in Ref. 2 is , and this means a 167-mm spatial interval for a moving speed of . It is obvious that this is not enough for axle counting. One of the solutions to this issue is using a scanless and wide FOV receiving optics and a small microelectromechanical system (MEMS) scanner only for transmitting the laser beam. Using this configuration, the issue of high-speed scanning can be solved. The sensors with this concept have already been reported in Refs. 678–9. However, these sensors used the pulsed method for the TOF measurement, and the size of the photodetector must be small (generally, much less than ) to respond to the short pulse, which is suitable for TOF measurement. Accordingly, the photodetector (and also the electrical receiving circuit) must be arrayed to realize a wide FOV and this made the sensor configuration drastically complex. This complexity is bad for everything, e.g., size, cost, performance stability, and so on. Here, we show the line scanning TOF laser sensor, which realizes all of the above-mentioned requirements, with a new simple configuration.