PURPOSE: To recombine many rolls arranged in upper and lower roll units to other constitution of rolls corresponding to the thickness of changed steel strip in a short time with little decrease in productive efficiency of the steel strip.

CONSTITUTION: A tension leveler is arranged with an upper traverse on which the upper roll unit is mounted and a lower traverse on which the lower roll unit is mounted in movable states in the direction orthogonally crossing with the passing direction of steel strip 1 in a housing 4. Plural sets of upper and lower traverses 20a, 20b, 21a and 21b mounted with roll units consisting of different constitution of rolls corresponding to the steel strip to be passed are linked with each other having a specific distance between them in the direction orthogonally crossing with the passing direction in the housing. A selected set of traverses among plural sets of upper and lower traverses is positioned at the specific position in the housing by a positioning means 37.