To provide an oscillation-proof fitting for a hanger bolt enabling itself to be prevented from being stopped against its oscillation rationally and safely.

There are provided a pair of gripping bodies 1 to be held against a side surface of a hanger bolt P. There are provided a pair of connection bolts 2 inserted into through-holes 1Aa, 1Ba passing through these gripping bodies 1. A pair of oblique supports 3 are connected to the connection bolts 2. The gripping bodies 1 are constituted by an outer gripping body 1A and an inner gripping body 1B. An oblique support 3 has an oscillation piece 3A and a fixed piece 3B that are integrally formed. There is provided a connector link 4 passing through the through-hole 1Aa of the outer gripping body 1A and a through-hole 3Aa of the oblique support 3. The outer gripping body 1A and the oscillation piece 3A are oscillatably connected by the connector link 4.