Working time monitoring device of preassembled workpiece

The utility model provides a working time monitoring device of a preassembled workpiece. The working time monitoring device comprises a worktable (10), an operation part detector (21), a material box detector (22) and a controller (30), wherein the worktable (10) is provided with an operation part placing area and a material box placing area, the operation part detector (21) is used for detecting whether an operation part (1) is arranged in the operation part placing area or not, the material box detector (22) is used for defecting whether a material box (2) is arranged in the material box placing area or not, the material detector (23) is used for detecting whether the material box (2) in the material box placing area contains material (3) or not, and the controller (30) is used for receiving signals sent by the operation part detector (21), the material box detector (22) and the material detector (23), and is provided with a timing unit. The working time monitoring device of the preassembled workpiece has the advantage that the labor intensity is decreased.