A roll profile measuring method uses a displacement detector mount provided movably in a reciprocating manner along an axial direction of a work roll, and a displacement detector set of two displacement detectors mounted at a center distance L.sub.c from each other on the displacement detector mount for measuring irregularities in the surface of the work roll in the axial direction of the work roll. The roll profile measuring method comprises: measuring irregularities in the surface of the work roll over the total length of the work roll by moving the displacement detector mount in the axial direction of the work roll; and processing a data stream of composite measured values obtained on the basis of the difference between measured data provided by the displacement detectors to determine the surface profile of the work roll in the axial direction of the work roll.