To measure the position of a radio wave emission source by a structure without requiring the measurement of arrival time difference or radio wave arrival direction and without increasing the circuit scale and size.

Moving bodies 1a, 1b each include a function of receiving a radio wave and transmitting a reception signal thereof and a function of obtaining and transmitting position information on the current position, and move at the same velocity in the same direction while holding a constant interval therebetween. A base station communication part 2 receives the reception signal and position information transmitted from the moving bodies. A position information processing part 4 calculates position and velocity information of the moving bodies 1a, 1b upon the signal reception from temporal variation of two pieces of position information output from the base station communication part 2. An emission source position calculation part 6 performs the calculation about the central position of the distance between the moving bodies 1a, 1b when the maximum value of the frequency difference is obtained, and estimates the position of the emission source of the same radio wave received by the moving bodies 1a, 1b on the basis of the calculation result.