An apparatus for determining position information of one or more UEs (User Equipments), which includes a plurality of Node Bs for transmitting propagation signals to UEs positioned in a specific cell, and generating predetermined data for measuring position information of the UEs on the basis of propagation signals received from the UEs; a GPS (Global Positioning System) auxiliary information manager for generating and storing GPS auxiliary information associated with a specific cell using a GPS satellite signal received via a built-in GPS receiver; and a RNC (Radio Network Controller) connected to the plurality of Node Bs, for receiving GPS auxiliary information from the GPS auxiliary information manager in response to a request signal of at least one Node B from among the plurality of Node Bs, optimizing the received GPS auxiliary information for every Node B, selecting the optimized GPS auxiliary information, and periodically transmitting the selected GPS auxiliary information to the UEs using a multicast method, in which the Node Bs broadcast the GPS auxiliary information received from the RNC to the UEs positioned in a corresponding cell over a broadcast channel. The apparatus uses a multicast method to differently transmit individual GPS auxiliary information needed for different cells, so that transmission efficiency increases and UEs can more quickly determine their positions.