Negative central shear discharges in JT-60U revealed an internal transport barrier (ITB) which is located at larger minor radii than those in other devices and is accompanied by a clear reduction in . In order to investigate this origin of the unique and favourable feature for future reactors, the discharge parameters were compared with those in DIII-D, where ITB was at smaller minor radii and less reduction in was observed. Strong negative magnetic shear was found to be related to the reduction in . The thin skin depth in JT-60U originating from high , together with the continuous decrease in , was effective in moving the ITB location to larger minor radii and in sustaining the strong negative shear.