A communication terminal receives acceptance data for gas cock opening created by a server, performs selection based on the received acceptance data, reads a two-dimensional barcode, and compares two-dimensional barcode data and target data stored in a storage device of the communication terminal; the sever sends the communication terminal a gas inspection item in which the target data is reflected; the communication terminal receives the inspection item in which the target data is reflected, checks an inspection result item created for the inspection item, and sends the checked inspection result item to the server; and the server gives permission for the gas cock opening based on the sent inspection result item, and sends a result of the permission to the communication terminal.