A machine tool includes a main machine, a pallet change unit, a main body cover, a machine entry door, an internal machine cover, and an internal entrance area. The main machine is configured to machine a workpiece. The pallet change unit is adjacent to the main machine. The main body cover is provided on the pallet change unit. The machine entry door is provided in the main body cover. The internal machine cover is connected to the machine entry door. The internal entrance area is defined by the machine entry door and the internal machine cover. The machine entry door and the internal machine cover are constructed to sweep the internal entrance area.

A processing machine comprises: a cover that is provided with an opening and defines a processing area; a first door that is slidable between a first position in which the opening is opened and a second position in which the opening is closed; a second door that is disposed to overlap with the first door inside the processing area and slidable between the first position and a third position that is opposite to the first position with respect to the second position and in which the second door cooperates with the first door to close the opening; and a rail member that includes a grooved portion and an abutment that engage with the first door and is provided at the second door to allow the second door to slide with respect to the first door. The grooved portion and the abutment are disposed outside the processing area.