To provide a ball joint having high rigidity at a low cost, absorbing the size tolerance of components, maintaining the excellent load resistance against a load and durability, reducing the damage by the stress at the time of assembling, and improving an yield.

A recess 28 is provided between first and second load reception sections 26, 27 provided at positions different in diameter and abutting on the bottom face section 8 of the housing 2 of the bearing seat 4 of a housing 2. A space section 32 is provided between first and second slide sections 30, 31 provided at positions different in diameter on the inner periphery of the bearing seat 4 slidably abutting on the spherical head section 16 of a ball stud 3. The size from the first load reception section 26 to the deepest section of the recess 38 in the axial direction of the inner chamber 12 of the housing 2 is formed smaller than the size from the first load reception section 26 to the deepest section of the space section 32. A elastic piece section 33 between the recess 28 and the space section 32 can be made large in thickness, and such damage as cracks and fractures can be prevented even when stress is applied to the bearing seat 4.