To reduce parts for vibration-proofing members in number, and enhance its assemblage by providing a mounting member integrally formed with a single weight, and a rubber member closely attached to the inner surface of the tip end part of a handlebar for a motorcycle, which is integrally formed with the mounting member.

The vibration-proofing device 10 is provided with a weight 36 roughly in a column shape, which is made of iron, and with a mounting member 32. And a rubber member 34 is pressed in a handlebar 40 in a state that the projected part 42 of the handlebar 40 enters into a groove 34A. In this case, the weight 36 is integrated with the mounting member 32 and the rubber member 34. Namely, since the vibration-proofing device 10 is thereby integrated with the amounting member 32, the weight 36 and the rubber member 34, there is no need for aligning the respective members in position and the like when the vibration-proofing device 10 is mounted to the handlebar 40, and furthermore its assembly can thereby be performed only by a simple operation such as a press-in work, the vibration-proofing device 10 can thereby be easily assembled.