An electronic key device for a vehicle which performs starting of the vehicle by performing ID verification against a portable electronic key unit includes an ID verification device, a decision device, and a vehicle starting control device. When the number of times that the result of ID checking by the ID verification device is negative and also the portable key unit is not present within the vehicle arrives at a predetermined value, a locked mode is set in which thereafter starting of the vehicle is prohibited unless a predetermined procedure is performed. When the result of ID checking by the ID verification device is affirmative and the portable key unit is not present within the vehicle, then no such predetermined number of times calculation for setting the locked mode is performed.