Patent ID: 8048174

Claim:
A theft prevention system comprising: an object control device for controlling a prescribed operation of an object targeted for theft prevention; and a mobile terminal device for instructing the object control device to control the prescribed operation, wherein the mobile terminal device includes: an instruction transmitting unit operable to transmit, to the object control device, a warning mode instruction indicating to set a warning mode; an electronic key receiving unit operable to receive a first electronic key from the object control device; an electronic key storage unit; an electronic key writing unit operable to write the received first electronic key to the electronic key storage unit as a second electronic key; and a control instructing unit operable to instruct the object control device to control the prescribed operation, using the stored second electronic key, and wherein the object control device includes: an instruction receiving unit operable to receive the warning mode instruction; a mode setting unit operable to set the warning mode on receipt of the warning mode instruction; an electronic key generating unit operable to generate the first electronic key on receipt of the warning mode instruction; an electronic key transmitting unit operable to transmit the generated first electronic key to the mobile terminal device; and an object control unit operable, when the warning mode has been set, to control the prescribed operation exclusively in accordance with the control instruction from the mobile terminal device using the second electronic key, wherein the instruction transmitting unit transmits to the object control device (i) a normal mode instruction indicating change from the warning mode to a normal mode and (ii) the second electronic key stored in the electronic key storage unit, wherein the instruction receiving unit receives the normal mode instruction and the second electronic key, wherein the object control device further includes a judging unit operable to judge whether the first electronic key generated by the electronic key generating unit and the received second electronic key match, and wherein the mode setting unit changes, when the first electronic key and the second electronic key match, from the warning mode to the normal mode.