To provide a small processing device with further improved processing efficiency.

This processing device 1 comprises a bed 2, a pair of workpiece supporting devices 10 and 20 installed on the bed 2, supporting a workpiece W from both ends, and capable of rotary driving the workpiece with a rotary axial line connecting supporting parts on both ends as a center, a processing table 30 installed on the bed 3 and moving backward in a direction crossing with the rotary axial line, and processing means T located on the processing table 30 and processing the workpiece W. The workpiece supporting device 10 and 20 comprise housing parts 11 and 21 fixed to the bed 2, sliding parts 12 and 22 capable of reciprocating relative to the housing parts 11 and 12 in a direction parallel to the rotary axial line, and engagement supporting parts 13 and 23 arranged on the sliding parts 12 and 22 and rotatably supporting the workpiece W with the rotary axial line as a center.