  We report the radiation hardness of a p-channel CCD developed for the X-ray
CCD camera onboard the XRISM satellite. This CCD has basically the same
characteristics as the one used in the previous Hitomi satellite, but newly
employs a notch structure of potential for signal charges by increasing the
implant concentration in the channel. The new device was exposed up to
approximately $7.9 \times 10^{10} \mathrm{~protons~cm^{-2}}$ at 100 MeV. The
charge transfer inefficiency was estimated as a function of proton fluence with
an ${}^{55} \mathrm{Fe}$ source. A device without the notch structure was also
examined for comparison. The result shows that the notch device has a
significantly higher radiation hardness than those without the notch structure
including the device adopted for Hitomi. This proves that the new CCD is
radiation tolerant for space applications with a sufficient margin.
