To provide a roll leveler apparatus the leveler roll releasing part of which is made into simple structure and the cost of which is reduced to a low cost and a method of changing its rolls.

Base blocks are provided freely ascendably and descendably over and under a line 3 on which a metal plate is run, a rotary block 6 is provided freely rotatably about a horizontal axis on the side of the line 3 of these base blocks and in an outer periphery of the rotary block 6 a plurality of roll units 7 having a leveler roll 16 which is brought into contact with the metal plate and with which the deformation of the plate is straightened are mounted separately in the peripheral direction and respectively changeably.