A positioning apparatus and method of a mobile terminal using a positioning server independently constructed on a network. The positioning apparatus includes a positioning server, independently constructed on a network, for collecting and storing/managing assistant data that includes orbit information and correction information of a satellite, and providing the assistant data or position information using the assistant data in response to an external request. The positioning server provides the position information of the terminal subject to positioning in response to the request for the position information of the terminal subject to positioning created from at least one network among a plurality of networks that share the positioning server. Accordingly, an accurate positioning result can be obtained with a cost for implementation of the positioning system reduced.