An operation unit cover moves between a position of covering an operation lever and a position of exposing the operation lever and holding the operation lever at a first operational position while being at the position of covering. A housing covers lateral sides and a top side of a case that cross a front side of the case and exposes the operation unit cover from the front side. A pivoting member pivots about a pivoting member's pivot shaft located above the operation unit cover, between a closed position of covering the operation unit cover and an opened position of exposing the operation unit cover and, while the pivoting member is at the closed position, the pivoting member forms a closed space between the pivoting member and the housing for accommodating at least the operation unit cover and holds the operation unit cover at the position of covering the operation lever.