A tire pneumatic pressure monitoring apparatus for monitoring tire pressure monitoring pneumatic pressure of each tire, comprising: a tire pneumatic pressure detecting means installed on the tire of each wheel to detect the pneumatic pressure acting on the tire; an acceleration sensor installed on the tire of each wheel to detect an acceleration in a prescribed direction acting on the tire; a transmitter arranged on each wheel to detect a rotational position of the wheel based on a detected value of the acceleration sensor and transmit the pneumatic pressure at a prescribed rotational position together with a unique information identifier for each transmitter as a wireless signal; a receiver arranged side of a vehicle body to receive the wireless signal; a wheel velocity sensor, which is arranged on the side of the vehicle corresponding to each wheel and which detects the velocity of the corresponding wheel; a rotational position detecting means arranged on the side of the vehicle and which detects the rotational position of each wheel when the wireless signal containing certain identification information is transmitted; characterized by a transmitting position determination means comprising a first rotating period determining part (4g; 11) that is adapted to determine a wheel rotating period of the wheel corresponding to the identification information when the wireless signal is transmitted based on the detected value of the acceleration sensor described above as the first rotating period (Tp), a second rotating period determining part that is adapted to determine the rotating period of the wheel corresponding to the identification information when the wireless signal is transmitted as the second rotating period (Ta) based on the detected value of the wheel velocity sensor, and a determination section that is adapted to transmit the wireless signal at the prescribed rotational position when the difference between the first rotating period (Tp) and the second rotating period (Ta) is equal to or smaller than a prescribed value (α); and a wheel position determination means that is adapted to determine the wheel, position of the transmitter corresponding to the identification information based on the rotational position of each wheel when the wireless signal is transmitted that is adapted to determine that transmission is made at the prescribed rotational position. a tire pneumatic pressure detecting means installed on the tire of each wheel to detect the pneumatic pressure acting on the tire; an acceleration sensor installed on the tire of each wheel to detect an acceleration in a prescribed direction acting on the tire; a transmitter arranged on each wheel to detect a rotational position of the wheel based on a detected value of the acceleration sensor and transmit the pneumatic pressure at a prescribed rotational position together with a unique information identifier for each transmitter as a wireless signal; a receiver arranged side of a vehicle body to receive the wireless signal; a wheel velocity sensor, which is arranged on the side of the vehicle corresponding to each wheel and which detects the velocity of the corresponding wheel; a rotational position detecting means arranged on the side of the vehicle and which detects the rotational position of each wheel when the wireless signal containing certain identification information is transmitted; characterized by a transmitting position determination means comprising a first rotating period determining part (4g; 11) that is adapted to determine a wheel rotating period of the wheel corresponding to the identification information when the wireless signal is transmitted based on the detected value of the acceleration sensor described above as the first rotating period (Tp), a second rotating period determining part that is adapted to determine the rotating period of the wheel corresponding to the identification information when the wireless signal is transmitted as the second rotating period (Ta) based on the detected value of the wheel velocity sensor, and a determination section that is adapted to transmit the wireless signal at the prescribed rotational position when the difference between the first rotating period (Tp) and the second rotating period (Ta) is equal to or smaller than a prescribed value (α); and a wheel position determination means that is adapted to determine the wheel, position of the transmitter corresponding to the identification information based on the rotational position of each wheel when the wireless signal is transmitted that is adapted to determine that transmission is made at the prescribed rotational position.