A system for measuring the position of an in vivo radio device is disclosed. The system comprises the in vivo radio device administered into a living organism, a plurality of ex vivo radio devices disposed outside of the living organism, and a position measuring device. The in vivo radio device includes a transmitter for transmitting a vital information signal or a position measuring signal. Each of the ex vivo radio devices includes a receiver for receiving the vital information signal or the position measuring signal. The position measuring device includes a position measuring unit for measuring the position of the in vivo radio device based on receiving characteristics of the vital information signal or the position measuring signal received by the ex vivo radio devices.