A wheel assembly position identifying apparatus (31, 50) configured to be mounted in a vehicle equipped with rotational position detecting sections, each of which detects a rotational position of one of wheel assemblies, the apparatus (31, 50) comprising: transmitters, each of which is provided in one of the wheel assemblies; and a receiver, which is provided in a body of the vehicle, wherein each transmitter includes a transmission section, which is configured to transmit a position detecting signal to the receiver, and a control section, which is configured to cause the transmission section to continuously transmit the position detecting signal for at least a predetermined transmission time, and the receiver includes a receiving section, which is configured to receive the position detecting signal, a measuring section, which is configured to measure a received signal strength indication (RSSI) of the received position detecting signal, and a wheel assembly position identifying section, which is configured to detect, more than once, a rotational position of each wheel assembly at which the RSSI has an extreme value, for each position detecting signal received during one rotation of the wheel assembly, characterized in that the wheel assembly position identifying section is configured to identify the position of the wheel assembly in which the corresponding transmitter is provided based on variation of the rotational position of the wheel assembly at which the RSSI has the extreme value. transmitters, each of which is provided in one of the wheel assemblies; and a receiver, which is provided in a body of the vehicle, wherein each transmitter includes a transmission section, which is configured to transmit a position detecting signal to the receiver, and a control section, which is configured to cause the transmission section to continuously transmit the position detecting signal for at least a predetermined transmission time, and a transmission section, which is configured to transmit a position detecting signal to the receiver, and a control section, which is configured to cause the transmission section to continuously transmit the position detecting signal for at least a predetermined transmission time, and the receiver includes a receiving section, which is configured to receive the position detecting signal, a measuring section, which is configured to measure a received signal strength indication (RSSI) of the received position detecting signal, and a wheel assembly position identifying section, which is configured to detect, more than once, a rotational position of each wheel assembly at which the RSSI has an extreme value, for each position detecting signal received during one rotation of the wheel assembly, a receiving section, which is configured to receive the position detecting signal, a measuring section, which is configured to measure a received signal strength indication (RSSI) of the received position detecting signal, and a wheel assembly position identifying section, which is configured to detect, more than once, a rotational position of each wheel assembly at which the RSSI has an extreme value, for each position detecting signal received during one rotation of the wheel assembly,