An antivibration device (10,70) comprising: a shaft-like first fixture (20,80) extending along an axis; a sleeve-like second fixture (30,90) having on at least one side an opening (31,91) larger than an external shape of the first fixture (20,80); and an antivibration base body (50,110) comprising a rubber elastic body and joined at least to the first fixture (20,80) and the opening (31,91) of the second fixture (30,90); wherein the first fixture (20,80) is equipped with a junction (21,81) having the antivibration base body (50,110) joined to an outer periphery; and a flange portion (25,85) connected to the junction (21,81) and having the antivibration base body (50,110) joined; wherein the junction (21,81) is equipped with a chamfer portion (22,82) where a corner connecting the flange portion (25,85) and the junction (21,81) is removed; a base portion (23,83) connected to the chamfer portion (22,82) in the axial direction; and an end portion (24,84) connected to the base portion (23,83) in the axial direction; and wherein at the junction (21,81), a first projection plane made by projecting at least the end portion (24,84) in a first direction orthogonal to the axis is set to be smaller in area than a second projection plane made by projecting at least the end portion (24,84) in a second direction orthogonal to the axis and the first direction, and a spring constant in the first direction is smaller than that in the second direction, characterized in that at the base portion (23,83), the area of the first projection plane and the area of the second projection plane are substantially the same in size. a shaft-like first fixture (20,80) extending along an axis; a sleeve-like second fixture (30,90) having on at least one side an opening (31,91) larger than an external shape of the first fixture (20,80); and an antivibration base body (50,110) comprising a rubber elastic body and joined at least to the first fixture (20,80) and the opening (31,91) of the second fixture (30,90); wherein the first fixture (20,80) is equipped with a junction (21,81) having the antivibration base body (50,110) joined to an outer periphery; and a flange portion (25,85) connected to the junction (21,81) and having the antivibration base body (50,110) joined; wherein the junction (21,81) is equipped with a chamfer portion (22,82) where a corner connecting the flange portion (25,85) and the junction (21,81) is removed; a base portion (23,83) connected to the chamfer portion (22,82) in the axial direction; and an end portion (24,84) connected to the base portion (23,83) in the axial direction; and wherein at the junction (21,81), a first projection plane made by projecting at least the end portion (24,84) in a first direction orthogonal to the axis is set to be smaller in area than a second projection plane made by projecting at least the end portion (24,84) in a second direction orthogonal to the axis and the first direction, and a spring constant in the first direction is smaller than that in the second direction, characterized in that at the base portion (23,83), the area of the first projection plane and the area of the second projection plane are substantially the same in size.