  We evaluate the single event tolerance of the X-ray silicon-on-insulator
(SOI) pixel sensor named XRPIX, developed for the future X-ray astronomical
satellite FORCE. In this work, we measure the cross-section of single event
upset (SEU) of the shift register on XRPIX by irradiating heavy ion beams with
linear energy transfer (LET) ranging from 0.022 MeV/(mg/cm2) to 68
MeV/(mg/cm2). From the SEU cross-section curve, the saturation cross-section
and threshold LET are successfully obtained to be $3.4^{+2.9}_{-0.9}\times
10^{-10}~{\rm cm^2/bit}$ and $7.3^{+1.9}_{-3.5}~{\rm MeV/(mg/cm^2)}$,
respectively. Using these values, the SEU rate in orbit is estimated to be
$\lesssim$ 0.1 event/year primarily due to the secondary particles induced by
cosmic-ray protons. This SEU rate of the shift register on XRPIX is negligible
in the FORCE orbit.
