A moving body includes a transmission device which simultaneously sends out a trigger signal and an ultrasonic signal modulated by pseudo random sequence data, and a reception device which detects a position of the moving body. The reception device includes two ultrasonic reception units The reception device includes a unit which calculates a correlation value between a waveform of the ultrasonic signal and a modulation reference waveform of a pseudo random sequence data assigned to the moving body The reception device includes a unit which calculates a time of propagation of the ultrasonic to arrive at the two ultrasonic reception units from a time point of reception of the trigger signal and a time point of detection of a first peak of the correlation value, and a unit which calculates a position of the moving body based on the ultrasonic propagation time and an interval length between the ultrasonic reception units.