A pipe-shaped fixture (100) to be attached to a housing (120) of a work machine includes a fixture body (102) having a front-end projection (110) and a rear-end projection (112) that make front and rear limits of a rubber cushion (104) that encloses the fixture body (102) closely and circumferentially. The front- and rear-end projections (110, 112) are connected to each other by a plurality of longitudinally extending ridges (114) formed at circumferential intervals. The ridges (114), front- and rear-end projections (110, 112) define a plurality of concavities (116) surrounded thereby on the outer circumference of the fixture body (102). The front- and rear-end projections (110, 112) cause longitudinal vibration of an operation rod (130) relative to the housing (120) to act as a compression force on the rubber cushion (104), and thereby suppress longitudinal vibration of the operation rod (130) while maintaining effects of suppressing horizontal and vertical vibrations, which are equivalent to those of existing vibration preventing structures.