  Mass composition is important for understanding the origin of
ultra-high-energy cosmic rays. However, interpretation of mass composition from
air shower experiments is challenging, owing to significant uncertainty in
hadronic interaction models adopted in air shower simulation. A particular
source of uncertainty is diffractive dissociation, as its measurements in
accelerator experiments demonstrated significant systematic uncertainty. In
this research, we estimate the uncertainty in $\langle X_{\rm max}\rangle$ from
the uncertainty of the measurement of diffractive dissociation by the ALICE
experiment. The maximum uncertainty size of the entire air shower was estimated
to be $^{+4.0}_{-5.6} \mathrm{g/cm^2}$ for air showers induced by $10^{17}$ eV
proton, which is not negligible in the uncertainty of $\langle X_{\rm
max}\rangle$ predictions.
