A tire information monitoring system includes a transmitting device, provided in a tire cavity region, for transmitting tire information, a receiving device, provided in a vehicle body, that receives the tire information from the transmitting device and determines a tire condition based on the tire information, and a setting device that transmits identification information and a criterion to the receiving device so as to set the identification information of the transmitting device and the criterion of the tire information used for determining the tire condition by the receiving device. The setting device can be a mobile telecommunication terminal device for setting the identification information and the criterion in the receiving device using a program downloaded via an external network.