A work apparatus to be mounted to a work vehicle includes: a pair of cylindrical masts 35 disposed erect on right and left sides of a vehicle body having a control valve; a boom 91 pivotally supported to the masts; an implement pivotally supported to the boom; a boom cylinder 60 for pivoting the boom; an implement cylinder 61 for operating the implement; a boom piping system communicating the control valve with the boom cylinder; and an implement piping system communicating the control valve with the implement cylinder; wherein a channel constituting member 84 constituting the boom piping system extends vertically within each mast; one end of the channel constituting member 84 extends to the outside at a lower portion of the mast to be connected with the control valve; and the other end of the channel constituting member 84 extends to the outside at an upper portion of the mast 35 to be connected with boom cylinder 60.
