Smart key system for vehicle and method of controlling the same

A smart key system for a vehicle, comprising:

• a communication unit configured to communicate with a smart key;
• a memory configured to store a code and a count that are included in a signal received from the smart key;
• and
• a processor configured to identify whether the smart key has been registered with the vehicle based on the signal, determine whether the count is normal by comparing the count with a pre-stored count, in response to a determination that the count is normal when the count is greater than the pre-stored count by a predetermined value or more, the processor configured to control a door of the vehicle in response to the code, and in response to a determination that the count is not normal, the processor configured to control the door to maintain a lock state,
• wherein in response to the door of the vehicle is controlled in response to the code, the processor is configured to determine whether a location of the smart key becomes a distance from the vehicle by a first distance or more,
• in response to a determination that the location of the smart key becomes the distance from the vehicle by the first distance or more, the processor is configured to control the door of the vehicle and update the pre-stored count.