The utility model provides a roll shifting device for a four-roll mill. The utility model belongs to the technical field of ferrous metallurgy equipment. The device comprises a working roller and a hydraulic device, the hydraulic device comprises a hydraulic cylinder, a hydraulic servo system communicated with the hydraulic cylinder and a piston rod; a moving block is arranged at the free end of the piston rod; the moving block is fixedly connected with a bearing box arranged at the end part of the working roller; a position detection device is arranged on the hydraulic device; the position detection device comprises a magnetostriction type sensor and a magnetic ring, the magnetic ring is fixedly connected with the moving block through a fixing piece, the magnetostriction type sensor is arranged on the hydraulic cylinder, the magnetostriction type sensor and the hydraulic servo system are electrically connected with the programmable controller, and the programmable controller is electrically connected with the computer. The utility model provides a roll shifting device for a four-roll mill, and aims to solve the technical problems that the existing roll shifting device for the four-roll mill is unreasonable in arrangement and uneven in hot bulge and abrasion degree distribution of a working roll.