A tire information communication system mounted on a vehicle includes a tire-pressure detector mounted on a tire wheel for detecting a pressure of a tire and transmitting a result of detection, a tire monitor mounted on a vehicle body for obtaining information about tire pressure from the tire-pressure detector, a tire transmission circuit provided in the tire-pressure detector for applying AC voltage containing information about tire pressure between the tire wheel and an annular conductor of the tire so that a radio wave is radiated from the annular conductor, a vehicle ground isolation provided in the tire monitor so as to receive the radio wave from the annular conductor thereby to be capable of generating AC voltage between the vehicle ground and itself, and a body-side receiving circuit provided in the tire monitor and connected to the vehicle ground and the vehicle ground isolation respectively for obtaining the information about the tire pressure from the AC voltage generated between the vehicle ground and the vehicle ground isolation.