A tool to be used for bending a sheet metal is selected and tool layout data is generated in advance that includes a tool ID of the selected tool, mounting position information, and information on a place where each tool is housed in a tool stocker. A display controller controls a display to display information on a place where a tool is housed. A tool collation unit collates a tool ID read by a reader of a tool retrieved by an operator from a tool stocker with a tool ID of a tool included in tool layout data. In a case where the read tool ID matches a tool ID of none of tools included in the tool layout data, the display controller controls the display to display a message indicating that the tool retrieved by the operator is an incorrect tool.

An offset number setting device that freely and easily sets an offset number for a tool to be mounted on a tool holder of a turret surface. A display linkage unit displays a turret surface selection screen on a display, displays a tool holder selection screen on the display by selecting the turret surface, and displays an offset number setting screen on the display by selecting the tool holder. An offset number is therefore set for the tool along with the selection of the turret surface on which the tool is mounted.