The present invention relates to an apparatus for detecting relative positioning information between rolls, and a method for measuring a roll alignment state by using same, and to an apparatus for detecting relative positioning information between rolls, and a method for measuring a roll alignment state by using same, the apparatus outputting a measurement result in real time so that a measurer can easily recognize the degree of parallelism and the degree of horizontality of a roll when a roll process line is formed, and thus an inter-roll alignment state can be checked or a measurement roll can be corrected according to the alignment state.