  We are developing monolithic pixel sensors based on a 0.2 $\mu$m
fully-depleted Silicon-on-Insulator (SOI) technology for HEP experiment
applications. The total ionizing dose (TID) effect is the major issue in the
applications for hard radiation environments in HEP experiments. To compensate
for TID damage, we have introduced a Double SOI structure which has a Middle
Silicon layer (SOI2 layer) in addition. We studied the recovery from TID damage
induced by $\mathrm{^{60}Co}~\gamma$'s and other characteristics of an
Integration-type Double SOI sensor. The Double SOI sensor irradiated to 100 kGy
showed a response for IR laser similar to of a non-irradiated sensor when we
applied a negative voltage to the SOI2 layer. We conclude that the Double SOI
sensor is radiation hard enough to be used in HEP experiments in harsh
radiation environments such as at Bell II or ILC.
