For InP-based InGaAs ridge quantum wires by selective molecule beam epitaxial (MBE) growth on [(1) over bar 10] oriented InP mesa-stripes, the origin of wire inhomogeneity and possible methods to improve the wire uniformity were investigated in detail. Appearance of extra-side-facets on (111)A sidewalls was the major reason for ridge waving, leading to the inhomogeneity of the wire. By introducing mis-orientation into the mesa-direction, the width of the extra-facets were drastically reduced, leading to the suppression of the ridge waving. On the other hand, growth on a mesa-stripe having wide and narrow width regions led to complete removal of the extra-side-facets and the ridge waving From the wide mesa region, resulting in formation of a highly uniform InGaAs wire segment having a length of several microns.