A tire pressure monitoring device for monitoring the air pressure of each tire, comprising: a tire pressure detection mechanism installed on the tire of each wheel and configured for detecting the air pressure of the tire; a transmitter installed on each wheel and configured for transmitting the air pressure information in a wireless signal with the identification information unique to each transmitter included in the wireless signal; a receiver mounted on the side of the vehicle body and configured for receiving the wireless signal; a rotational position detection mechanism (8, ABSCU6) installed on the vehicle body in correspondence with each wheel and configured for detecting a rotational position of each wheel and for outputting rotational position information (zt1, zt5) at a predetermined time interval to a communication line; a vehicle body side rotational position estimate mechanism installed on the vehicle body and configured for estimating the rotational position of the transmitter at the time of transmission based on the received information from the transmitter and the rotational position information (zt1, zt5) of the wheel input via the communication line, and a wheel position determination mechanism for identifying a position (FR, FL, RR, RL) of the wheel on which the transmitter is installed and based on the estimated rotational position and the identification information included in the wireless signal, wherein the rotational position estimate mechanism is configured to estimate the rotational position at the time of transmission from the transmitter and based on the rotational positions (zt1, zt5) of the wheel which are input immediately before a receiving start of the wireless signal from the transmitter and immediately after the receipt completion respectively input via the communication line, the time (t1, t5) of input of rotational position of the wheel, and the receiving start time or the receipt completion time. a tire pressure detection mechanism installed on the tire of each wheel and configured for detecting the air pressure of the tire; a transmitter installed on each wheel and configured for transmitting the air pressure information in a wireless signal with the identification information unique to each transmitter included in the wireless signal; a receiver mounted on the side of the vehicle body and configured for receiving the wireless signal; a rotational position detection mechanism (8, ABSCU6) installed on the vehicle body in correspondence with each wheel and configured for detecting a rotational position of each wheel and for outputting rotational position information (zt1, zt5) at a predetermined time interval to a communication line; a vehicle body side rotational position estimate mechanism installed on the vehicle body and configured for estimating the rotational position of the transmitter at the time of transmission based on the received information from the transmitter and the rotational position information (zt1, zt5) of the wheel input via the communication line, and a wheel position determination mechanism for identifying a position (FR, FL, RR, RL) of the wheel on which the transmitter is installed and based on the estimated rotational position and the identification information included in the wireless signal, wherein the rotational position estimate mechanism is configured to estimate the rotational position at the time of transmission from the transmitter and based on the rotational positions (zt1, zt5) of the wheel which are input immediately before a receiving start of the wireless signal from the transmitter and immediately after the receipt completion respectively input via the communication line, the time (t1, t5) of input of rotational position of the wheel, and the receiving start time or the receipt completion time.