To provide a laser processing device capable of easily and accurately adjusting the flatness of a workpiece bearing board.

The laser processing device includes a plurality of support units which are disposed under the workpiece bearing board to support the workpiece bearing board and can raise and lower a support position, drive units which move the support units up and down, a displacement measuring unit which measures the upper surface shape of the workpiece bearing board, a control unit which controls the drive units and can obtain measurement results from the displacement measuring unit, and a memory unit which stores relation data of the relation between an operation rate of each drive unit and a displacement rate of the workpiece bearing board, based on the displacement of the upper surface shape of the workpiece bearing board resulting from operation of each drive unit. The control unit receives the measurement results from the displacement measuring unit and calculates a displacement rate of the workpiece bearing board, which is to be displaced by operation of each drive unit, in order to adjust the upper surface shape of the workpiece bearing board to give the upper surface shape a given flatness, determines an operation rate of each drive unit referring to the relation data stored in the memory unit, based on the displacement rate, and operates each drive unit based on the operation rate.