To inform each of family members who has come back or is going out by the kinds of melody sounds after distinguishing them.

A key remote control 1 transmits an unlock signal of a particular frequency given to each family member possessing the remote control unit. An unlock control unit 22 received by the unlock signal by the first receiving portion 21a transmits the received unlock signal to a frequency detector 23 and a control portion 32. The frequency detector 23 detects the frequency of the received release signal and transmits the frequency information detected to a particular section 31 of the family members and the particular section 31 determines the particular family member based on the frequency information from the frequency detector 23. The control portion 32 extracts a melody sets for the relevant family member stored in a data base 33 based on the family member information determined by the family member particular section 31 and the unlock signal from the lock and unlock control section 22 and these are played back and its melody sound is generated from the information section 35.