To provide a lost belonging prevention system and its entrance machine and exit machine which are utilized at the time a user enters or leaves a control area such as a station yard.

An IC card reader/writer is arranged on an entrance side and an exit side of entrance/exist machines. When an ID of a wireless tag attached to belongings of a user is determined OK in its verification, the user carrying this IC card is requested to touch the IC card reader/writer arranged on the exit side with the IC card. With the touch of the IC card, the user is allowed to enter with his/her belongings, and an entrance bit of the wireless tag registered in the IC card is written. At the exit machine configured similarly to the entrance machine, when the ID of the wireless tag is determined OK in its verification, the user is requested to touch the IC card reader/writer with the IC card. With the touch of the IC card, the user is allowed to exit with his/her belongings, and the entrance bit of the wireless tag registered in the IC card is erased.