BALL JOINT

A ball joint which is capable of ensuring the retention strength to resist a force tending to pull out or pry out a ball portion of a ball stud while ensuring sealing performance of the dust cover is provided. A ball joint 100 includes a bearing seat in the form of a resin ball seat 130 which is provided within a seat-accommodating portion 121 of a metal socket 120 for slidably and rotatably receiving a ball portion 113 of a ball stud 110. The seat-accommodating portion 121 is formed such that its end portion through which the stud portion 111 passes extends towards the stud portion 111 beyond the spherical center O of the ball portion 114. The ball seat 130 has a covering portion 133 formed on the outer side of a seat opening portion 132 of a ball-accommodating portion 131 which has a spherical shape in conformity to a sliding surface 114a of the ball portion 114 of the ball stud 110. The covering portion 133 is formed by bending the seat opening portion 132 such that it covers the outer periphery of the opening portion of the seat-accommodating portion 121 of the socket 120.