To provide a machining device capable of highly accurately machining a shaped surface of a lens at a plurality of parts on the surface of a workpiece such as a lens array die.

The machining device is composed as follows. A Z-axis mechanism part for vertically moving a main spindle is provided to a column erected on a bed. A U-axis table, to which a tool is mounted so as to be rotationally driven around its axial center, and a U-axis mechanism part, which moves the U-axis table in the U-axis direction orthogonal to the Z-axis direction, are provided to the lower end of the main spindle. The tool is rotationally driven around its axial center while the main spindle is being rotationally driven when the workpiece is machined. The positional control of the tool is executed by a controller for controlling the U-axis mechanism part and the Z-axis mechanism part.