To provide a transmitter of a tire condition monitor which can perform correct reception by a receiver, and the tire condition monitor.

When the vehicle traveling is detected by a vehicle speed sensor 34 of each transmitter 30 is detected after a vehicle is stopped once, a transmission controller 31 of each transmitter 30 calculates the delay time different from each other based on a specific ID code which is registered in a ROM in advance. After the delay time different from each other is elapsed, each transmitter 30 measures the pneumatic pressure and the temperature in the tire at the interval of 15 seconds, and returns the data at the interval of 10 minutes. Therefore, the data from the transmitter 30 is not transmitted at the same timing. As a result, the radio waves from the transmitter 30 never interfere with each other. Thus, the data from each transmitter 30 can be correctly received by the receiver.