A technology downsizing a control panel unit is provided. The control panel unit for a machine tool comprises a casing, a duct, and a fan. The casing has an openable door. A control device is arranged in an internal space, which is closed when the door is closed. The duct has a groove and a ventilation opening. The groove is closed at a closed end and open to the internal space at an open end. The ventilation opening connects the groove with the internal space in a position nearer the closed end than the open end. The duct is fixed to an inner wall of the casing in such manner as the groove faces the inner wall. The fan is mounted on the ventilation opening. The air in the internal space is taken into the groove enclosed by the inner wall and the duct by the operation of the fan.