In this work we propose a new moving optical wedge interferometer for Fourier transform spectroscopy. This is based first on using two couples of wedges, one wedge arm in each arm. For each couple of wedges there is a mirror attached to one wedge. Second, we move one wedge of each couple. The moving wedges in both arms are fixed to each other so they both move rigidly. This increased the factor multiplied by the wedges motion to obtain optical path difference (OPD) twice. This factor showed dependence on the wedge refractive index and wedge angle. First, this factor is less than two which suppresses motion error effects of the wedge. This is compared to motion of mirror in ordinary Michelson interferometer (MI) where the factor is two. Then this factor increases more than two and less than four. This suppresses motion error effects when compared to pair motion error with factor of four. Also, the increase of this factor increases the span of OPD thus improves resolution. Further, the wedge interferometer was proposed to suppress motion errors when compared ordinary MI but it may produce errors when the surface of the wedge is not flat. So, we discuss the problem of surface non-flatness of the wedge. We used the visibility to model the deterioration of the interferogram due to surface non-flatness.