Motor vehicle drunk-driving-preventing device

The invention relates to a motor vehicle drunk-driving-preventing device which comprises an alcohol gas concentration detection, alarm and breaking device and alcohol gas concentration sensors. The alcohol gas concentration sensors are connected with the signal input end of the alcohol gas concentration detection, alarm and breaking device and fixed inside a steering wheel of a motor vehicle. Detection gas holes are formed in the positions, where the alcohol gas concentration sensors are fixed, of the steering wheel. Gas guiding leather cups are fixed at the positions, where the detection gas holes are formed, of the steering wheel. The motor vehicle drunk-driving-preventing device is simple in structure, convenient to install and capable of truly achieving the drunk-driving-preventing aim.