This paper describes the relation between the right angle error and the accuracy of a convex spherical shape on works when using lip type grinding wheels. The right angle error between a work axis and an inner cone surface of a lip type grinding wheel brings the effect upon the spherical shape on the work, and deforms its shape to aspherical. The expressions of this aspherical shape are formulated, and the correlative equations between the right angle error values and the patterns obtained from interference fringes of this aspherical shape are also made out. The experiment is performed for the optical glass rod work (φ10×L100mm) using a lip type grinding wheel filled up with 7 μm diamonds. Following conclusions are obtained : (1) When a work axis and an inner cone surface of a lip type grinding wheel are not at right angles to each other, the spherical shape obtained on the work deforms to aspherical having a cone shape at the center, and having other spherical shape (its center is not on the work axis) at the peripheral part of the surface of revolution. (2) As a work axis inclines toward the opened side of a grinding wheel and its value Δγ is 7.0×10-3 rad, the peak shape is formed at the center and about 16 pieces of interference fringe appear on the work in agreement with the calculated results on the experiment.