To provide an electronic lock system with high security capable of locking and unlocking a key by utilizing the ring tone melody of a cellular phone.

The music data on desired ring tone melody and locking signals obtained by enciphering the music data are downloaded from a server device 1 in an ring tone melody providing site of the cellular phone to the cellular phone 2 of a user. In locking, the enciphered locking signals are reproduced by the cellular phone 2 and input into a locking device 3 by voice to close the electronic lock 32. The locking device 3 comprises a function for recovering the music data on the original ring tone melody by reading the enciphered locking signals. In unlocking, the music data on the ring tone melody not enciphered by the cellular phone 2 is reproduced and input into a lock control device 31 by voice. The lock control device 31 is so formed that opens the electronic lock 32 when the music data input by voice matches the recovered secondary music data by comparing them with each other.