PURPOSE: To measure an exposure dose at an access area, by mounting a transmitter in a measuring device for monitoring an individual and providing a directional antenna for receiving a transmitting signal at every region and linking a calculator to a receiving signal processing circuit.

CONSTITUTION: A radiation worker pulls off a dosemeter 10 having a pulse modulator mounted therein from a charge device 6 when enters a control area 11 and holds an individual identification card 9 to enter an automatic reading access apparatus 1. When the card 9 is inserted in an insert port 8, an individual control number is transmitted to a calculator 20 and, when the dosemeter 10 is inserted in an insert port 7, a dosemeter number is transmitted to the calculator 20. When the worker takes out the card 9 and the dosemeter 10 to enter a working area 13, the radio wave transmitted from the dosemeter 10 is received by an antenna 14 with a beam width having directionality to be transmitted to a receiver 17. An entry time is processed by the calculator 20. The exposure dose of radiation when the worker enters the area 13 is calculated from the difference between the accumulated exposure dose at the time of leaving and that at the time of entering. By this method, the exposure dose in an access area can be measured.