We calculate the kaon semileptonic form factors using the two
sets of the PACS10 configuration, whose physical volumes are more than
(10 fm)$^4$ at the physical point. The lattice spacings are 0.063 and 0.085 fm.
The configurations were generated using the Iwasaki gauge action and $N_f=2+1$
stout-smeared nonperturbatively $O(a)$-improved Wilson quark action. From the
momentum transfer dependence of the form factors, we
evaluate the slope and curvature for the form factors at the zero momentum
transfer. Furthermore, we calculate the phase space factor, which is used
to obtain $|V_{us}|$ through the kaon semileptonic decay. These results are
compared with previous lattice results and experimental values.