id and the user id delivered thereto in the step 1 3 the user managing section 32 searches whether or not the user id delivered thereto is already registered and since the user id is already registered extracts user managing information of the user having the user id herein the user managing information including the user id associated with the terminal id of the terminal a is extracted thus the user managing information corresponding to the user id is already present in this event the terminal id of the user managing information is rewritten from that of the terminal a into that of the terminal b thus the user managing information is updated and stored 4 the user managing section 32 delivers an information deletion request to the position information managing section 31 together with the terminal id of the terminal a in order to delete the position managing information of the terminal a already registered 5 the position information managing section 31 searches and retrieves the position managing information corresponding to the terminal id delivered thereto in the step 4 and deletes the position managing information after the position id corresponding to the terminal id is extracted therefrom 6 in order to inform the terminal a of deletion of information the position information managing section 31 extracts the position id from the position managing information retrieved in the step 5 and delivers a deletion request to the base station equipment 21 herein located at the position a 7 the base station equipment 21 transfers the deletion request to the terminal a 8 the terminal a delivers a deletion completion notice to.