The object of the invention is to provide a vehicle key capable of preventing the drunken driving. The vehicle key comprises a key portion with the forward end portion thereof insertable into the key hole of the vehicle such as a train, a motor bike and an automobile, a holder portion arranged at the base end portion of the key portion, a projection member projected from the holder portion along the key portion, a spring for urging the projection member in the direction of projection, a breath component detection means for detecting the alcohol contained in the breath of the user, and a lock mechanism for locking the projection member in a projected state in accordance with the detection result of the breath component detection means.