  The gravitational lensing magnification or demagnification due to large-scale
structures induces a scatter in peak magnitudes of high redshift type Ia
supernovae (SNe Ia). The amplitude of the lensing dispersion strongly depends
on that of density fluctuations characterized by the $\sigma_8$ parameter.
Therefore the value of $\sigma_8$ is constrained by measuring the dispersion in
the peak magnitudes. We examine how well SN Ia data will provide a constraint
on the value of $\sigma_8$ using a likelihood analysis method. It is found that
the number and quality of SN Ia data needed for placing a useful constraint on
$\sigma_8$ is attainable with Next Generation Space Telescope.
