A pipe mounting structure of a work machine that has a lightweighted structure and is able to stably mount many pipes thereon includes a structure for mounting pipes to a work machine such as a demolition machine. The structure includes at least a pair of protruding portions formed by upwardly protruding end portions of side plates of a front boom, a bridge member that is bridged between the pair of protruding portions, and connecting portions that connect the protruding portions and the end portions of the bridge member to each other, and the plurality of pipes are fixed to the bridge member.
