A reprogramming method of a vehicle includes authenticating a diagnostor; receiving integrated firmware comprising a plurality of firmwares that correspond to a plurality of target controllers, respectively, from the diagnostor that is completely authenticated; authenticating the integrated firmware; encrypting and storing the plurality of firmwares included in the integrated firmware; and generating encryption keys that corresponds the plurality of target controllers, respectively apparatus. The encrypting and storing comprises encrypting and storing the plurality of firmwares to the encryption keys that correspond to the plurality of firmwares, respectively.