Key for vehicle

[Object] The object of the invention is to provide a vehicle key capable of preventing the drunken driving. [Configuration] The vehicle key is adapted for outputting a start permit signal to a vehicle such as a train, a motorbike, or an automobile, and for either starting a prime mover of the vehicle or setting the prime mover in a ready state for starting. The key has a hold of portion 200 and comprises: a signal output means 900 for outputting the signal; a breath component detection means 500 for detecting at least one of alcohol and drugs contained in the breath of a user; and a prevention means 1000 for preventing the output of the start permit signal to the vehicle from the signal output means in accordance with a detection result of the breath component detection means.