To provide a device for preventing intoxicated driving in a vehicle.

Expiration of a driver is breathed out to an alcoholic smell detection cylinder 2 mounted to the vehicle and an amount of alcoholic of the expiration is detected by an alcoholic detection sensor 8 mounted to the cylinder 2. Therefore, operation of the device cannot be made uncertain or non-operated by vicious act of the driver as mentioned above. Further, when the driver breathes from the nose and immediately breathes out or air is pressure-fed into a vessel by an air pump or the like, an O2 (oxygen) sensor 10 mounted to the vessel detects that it is not the expiration from an amount of oxygen in the vessel and makes starting of an engine inoperable. It can be also mounted to a two-wheel vehicle.