An in-vivo information acquiring system 1 includes a capsule medical apparatus 10 that is:introduced into a subject 100 and then transmits data including acquired information as a wireless signal and a receiving apparatus 30 that receives the wireless signal by using a plurality of external antennas 20. The in-vivo information acquiring system 1 includes a center frequency adjuster that adjusts the center frequency of a carrier wave that carries data a frequency modulator that modulates the frequency of the carrier wave according to data input and a frequency switching unit that switches the resonance frequency of an external resonance circuit that outputs data to outside.
