To provide an expansion anchor to be surely attached over the relatively large diameter of the attaching hole of a holder.

An expansion anchor 1 for fixing an attaching means such as a cable holder to the attaching hole 2 of a holder 3 is provided with an anchor head part 4 abutted on the surface side 5 of the holder 3, an anchor shaft part 6, and two anchor blade pieces 7 located in the anchor shaft part 6 to form a sharp angle therebetween. When introduced to the attaching hole 2, these anchor blade pieces 7 are swung to be elastically bent to approach each other, and after the passage through the attaching hole 2, these are expanded again over the diameter of the attaching hole 2 to move the pulling-out of the expansion anchor 1 from the attaching hole 2. Two stoppers 8 and 8' engaged with the inner edge 9 of the attaching hole 2 are protruded from the anchor shaft 6 perpendicularly to the same or from the anchor head part 4 in parallel with the anchor shaft 6, each anchor blade piece 7 is provided with a rear side projection 10 to be engaged with the inner edge 9 of the attaching hole 2, and the stoppers 8 and 8' and the projection 10 are provided within different non-stacked ranges in the width direction of the anchor shaft 6 perpendicular to the swinging surface of the anchor blade piece 7.