To automatically adjust a clearance according to a plate thickness and material without using a tool for improving cutting accuracy and productivity.

A movable table 11 having a lower edge 9 for shearing a workpiece in cooperation with an upper edge 7 fixed to a ram 5 on a base 3 is provided with an automatic clearance adjusting device 13 having an elastic element 15 being free in approach-to and separation-from the upper edge 7, and in addition, provided with a positioning device 19 composed of a guide member 21 to bring the movable table 11 into sliding contact with the base 3 and a table pressing member 23. Thus the automatic adjustment of the clearance is possible and cutting accuray and productivity can be improved.