According to an electronic key device capable of wirelessly controlling a lock system and transmitting control authentication of a lock system, a system therefor, and a method therefor, which are presented in the present invention, an operation of the lock system is controlled by communicating with the lock system, and an electronic key can be simply transmitted and rented, at a long distance through a communication network, by communicating with another electronic key device and granting operation control authority of the lock system to the other electronic key device.