Patent ID: 8740772

Claim:
A position information estimation system comprising: a body-insertable apparatus that is inserted into a subject and moves through an inside of the subject; a receiving unit that receives information from the body-insertable apparatus; and an information processor that performs processes on the information acquired from the receiving unit, wherein the receiving unit includes an acquisition antenna that includes a plurality of receiving antennas and acquires the information from the body-insertable apparatus, and the receiving unit or the information processor includes: a calculation unit that calculates difference values between signal levels acquired from the plurality of receiving antennas and corresponding signal levels previously acquired from the plurality of receiving antennas; a determination unit that compares each of the difference values and a threshold and determines whether to estimate position information; and a position information estimation unit that, when the determination unit has determined that it is necessary to estimate the position information, estimates position information of the body-insertable apparatus.