This paper discussed the lower-hybrid-drift instability in a simple magnetopause structure in which tbe charge separation electric field is completely neutralized and the total pressure is a constant. The magnetic field directions are assumed to be parallel each other crossing the magnetic boundary. The equilibrium distribution functions presented by W. Alpers is used to calculate the growth rate of the LHD instability and the field energy density. The anomalous resistivity is also evaluated. If the thickness of the magnetopause is near two Larmor radius of thermal ions, the instability growth rate is 0.26 ωLH (ωLH is the lower hybrid frequency) and the anomolous resistivity is 10-5 sec. As the thickness increases, the growth rate and the anomalous resistivity decrease rapidly.