To provide a method for preventing the occurrence of fatigue crack simply without removing an existing soleplate and to provide a cutting device used in this method.

Although the bridge girder 1 of a bridge is installed on an abutment 3 through a support 2, the soleplate 5 like a flat plate is fixed between the bridge girder 1 and the support 2 by fillet welding usually. A welded joint part of the soleplate 5 and a lower face of a lower flange 1a is horizontally cut by the cutting device 10 in which a disc grinder having a flat upper face is loaded on an XY table 12 to cut and remove the soleplate 5 from the lower flange 1a and exchange a mounting bolt 8 tightening the soleplate 5 on the lower flange 1a with a mounting bolt having such strength that does not necessitate fillet welding.