An N-channel MOS field-effect transistor on an SOI substrate including a
source electrode, drain and gate electrodes both disposed via a field
oxide film, a gate oxide film, a high concentration P-type layer, a high
concentration N-type layer contacting the source electrode and the gate
oxide film, a high concentration N-type layer contacting the drain
electrode, a p-body layer contacting the high concentration P-type and
N-type layers and the gate oxide film. In this transistor, an N-type layer
with a concentration higher than that of a drain region contacting the
p-body layer constitutes a region covering at most 95% of the source-drain
distance. Further, an N-type region having a concentration from
3.times.10.sup.16 /cm.sup.3 to 1.times.10.sup.22 /cm.sup.3 is provided
near a buried oxide film under the drain electrode.
