To provide a preset adjusting device capable of precisely and easily showing standard projected quantity from an adjusting nut to a tool head end part in accordance with a kind of a tool and adjusting projected quantity to the standard projected quantity.

The preset adjusting device 10 to adjust the projected quantity T from an adjusting member 4 to head end part 1a to the previously set standard projected quantity Tb by providing the adjusting member 4 free to move along the axial direction of the tool 1 on a holder 2 on which the tool 1 is installed is furnished with a base 11, a holding means 12 to hold the holder 2, a standard projected quantity memory means 26b to store the standard projected quantity Tb to correspond with a plural number of kinds of the tools 1, an input means 30 to input a tool data, a standard projected quantity reading means 25 to read the corresponding standard projected quantity Tb from the standard projected quantity memory means 26b in accordance with the input tool data and a display means 18 to display a preset mark 20 at a position corresponding to the standard projected quantity Tb, and the head end part is positioned to the preset mark 20 by adjusting the adjusting member 4.