To provide a hydraulic piping structure preventing hydraulic piping from being exposed and impairing its appearance.

The hydraulic piping leading from a control valve 40 and connected to a hydraulic actuator for a front attachment is installed on the back of a boom 31BC and comprises boom piping and body side piping connected to the control valve 40. The body side piping has a relay point P provided between the control valve 40 and a pin 31BP and comprises first body side piping between the boom piping and the relay point P and second body side piping between the relay point P and the control valve 4. The relay point P is placed in a position such that the first body side piping is always projecting downwards while the required length of the first body side piping varied by the raising or lowering motion of a boom 31B and the minimal required bending R of a rubber hose of the first body side piping are met.