A lateral processing machine, comprising: a bed; a floor surface X-axis guide disposed on an upper surface of the bed; a first moving column guided by the floor surface X-axis guide to reciprocate in X direction; a first Y-axis guide disposed on the first moving column; a first processing unit guided by the first Y-axis guide to reciprocate in Y direction, the first processing unit includes a first ram that rotatably supports a first spindle and advances or retracts in Z direction; a second processing unit guided by the first Y-axis guide to reciprocate in Y direction, the second processing unit includes a second ram that rotatably supports a second spindle and advances or retract in Z direction; and an expansion cover including, a box cover disposed on the bed, a first X box extending in Y direction inside the box cover to reciprocate in X direction together with the first moving column, a first X telescopic cover configured to cover between the first X box and the box cover, a first Y box receiving the first ram to extend through, the first Y box configured to reciprocate in Y direction inside the first X box, a second Y box receiving the second ram to extend through, the second Y box configured to reciprocate in Y direction inside the first X box, a first Y telescopic cover configured to cover between the first Y box and the first X box, a second Y telescopic cover configured to cover between the first Y box and the second Y box, and a third Y telescopic cover configured to cover between the second Y box and the first X box. a bed; a floor surface X-axis guide disposed on an upper surface of the bed; a first moving column guided by the floor surface X-axis guide to reciprocate in X direction; a first Y-axis guide disposed on the first moving column; a first processing unit guided by the first Y-axis guide to reciprocate in Y direction, the first processing unit includes a first ram that rotatably supports a first spindle and advances or retracts in Z direction; a second processing unit guided by the first Y-axis guide to reciprocate in Y direction, the second processing unit includes a second ram that rotatably supports a second spindle and advances or retract in Z direction; and an expansion cover including, a box cover disposed on the bed, a first X box extending in Y direction inside the box cover to reciprocate in X direction together with the first moving column, a first X telescopic cover configured to cover between the first X box and the box cover, a first Y box receiving the first ram to extend through, the first Y box configured to reciprocate in Y direction inside the first X box, a second Y box receiving the second ram to extend through, the second Y box configured to reciprocate in Y direction inside the first X box, a first Y telescopic cover configured to cover between the first Y box and the first X box, a second Y telescopic cover configured to cover between the first Y box and the second Y box, and a third Y telescopic cover configured to cover between the second Y box and the first X box. a box cover disposed on the bed, a first X box extending in Y direction inside the box cover to reciprocate in X direction together with the first moving column, a first X telescopic cover configured to cover between the first X box and the box cover, a first Y box receiving the first ram to extend through, the first Y box configured to reciprocate in Y direction inside the first X box, a second Y box receiving the second ram to extend through, the second Y box configured to reciprocate in Y direction inside the first X box, a first Y telescopic cover configured to cover between the first Y box and the first X box, a second Y telescopic cover configured to cover between the first Y box and the second Y box, and a third Y telescopic cover configured to cover between the second Y box and the first X box.