A tire air pressure detection system, able to prevent a strong electric field or strong radio interference from affecting transmitters and causing mistaken data relating to tire air pressure to be sent out and a driver from being mistakenly warned, having transmitters with controllers, detection circuits, and sensing units and a receiver, the controllers stopping detection signals from being sent to the receiver at current transmission timings when the detection circuits detect a strong electric field or radio interference in the interval from a previous communication timing to a current communication timing, whereby even if the strong electric field or radio interference affects detection signals from sensors provided at the sensing units, the transmitters can be prevented from sending out mistaken data relating to tire air pressure.