The experimental results on drag increment caused by internal waves, which are generated by a Rankine ovoid towed horizontally at constant velocities in a two-layer stratified water (a strong pycnocline) initially at rest, are presented. The drag increment due to stratification is obtained experimentally as a function of internal Froude number Frd and Reynolds number Re. From the results, it is shown that as a function of Frd or Re, an increment in mean drag coefficient due to stratification △Cd has both increasing and decreasing region attributable respectively to internal wave and to collapse of mixing fluids in the wakes. A most significant result shows that when Frd = 0.838 there exists a maximum of △Cd, which is equal to 0.05 in the exciting region of the strong internal wave generation. The experimental results on drag increment caused by internal waves, which are generated by a Rankine ovoid towed horizontally at constant velocities in a two-layer stratified water (a strong pycnocline) initially at rest, are presented. experimentally as a function of internal Froude number Frd and Reynolds number Re. From the results, it is shown that as a function of Frd or Re, an increment in mean drag coefficient due to stratification △ Cd has both increasing and decreasing region attributable respectively to internal wave and to collapse of mixing fluids in the wakes. A most significant result shows that when frd = 0.838 there exists a maximum of ΔCd, which is equal to 0.05 in the exciting region of the strong internal wave generation.