Display for cutting tool

A root canal length measuring device includes a display for displaying a control mode figure indicating an execution control mode executed among a plurality of control modes and a control unit for controlling the display to display the figure. A plurality of elements for displaying the control mode figure include a shaft portion extending in an arc shape or a fan shape and a clockwise head portion and a counterclockwise head portion indicating a first direction and a second direction as rotation directions of a cutting tool, respectively. The control unit controls the display according to the execution control mode in a root canal treatment device so that, among the plurality of elements, an entirety or a part of the shaft portion and the clockwise head portion and/or the counterclockwise head portion are displayed on the display.