The present invention introduces a location determining system. The location determining system includes a reader array and a location determining engine server. The reader array includes three readers, where each reader includes a plurality of reader groups that receives a tag information signal transmitted from the tag, generates a PN code generated from inside, correlation and standard deviation of the correlation, and bypasses the tag information signal, in a case a ratio of correlation and standard deviation of the correlation is greater than a predetermined critical value. The location determining engine server determines a final location value relative to the tag, using the tag information signal having a time difference of tag information signals received from the three readers forming each reader group among the tag information signals bypassed by the plurality of reader groups smaller than a predetermined marginal time difference.