To prevent generation of voids, by appropriately selecting the shape of a flange of a silicone bushing.

In a flange used for a silicone bushing manufactured by attaching, in a die, a tube 1 mounted with the flange 2 on either end thereof, injecting a silicone of high viscosity into the die, and molding the silicone around the tube 1, the radius R1 of curvature of a circular-arc corner part of an end part A of a projecting part 2a provided on the flange 2 and contacting with the tube 1 is adapted to satisfy R1≤2 mm. This arrangement prevents accumulation of air in a portion where the end part A of the flange contacts with the tube 1, and thus generation of voids can be prevented.