A method of measuring inter-device relative coordinates performed by a first device communicating with at least one second device belonging to a group to which the first device belongs includes measuring a range between the first device and the second device through communication with the second device; receiving range information between a plurality of second devices from the second device; calculating a plurality of solutions for inter-device relative coordinates using information about the range between the first device and the second device and the range information between the plurality of second devices; and deducing a true solution among the plurality of solutions for the inter-device relative coordinates using coordinates of each of the first device and the at least one second device with respect to a reference origin that is calculated using a Pedestrian Dead Reckoning (PDR) technique.