This paper presents the results of a series of experiments performed to examine the validity of a theoretical analysis for evaluation of machining error in ball end milling of spherical surface. In the analysis, the trochoidal paths of cutting edges are considered in the evaluation of chip geometry. The cutting forces are evaluated based on the theory of oblique cutting. The machining errors resulting from cutting force induced tool deflections are calculated at various parts of the machined surface. The experiments are carried out at various cutting conditions for convex spherical surface, and the influences of cutting mode and milling position angle on machining error are examined.