  The $\eta_c$ meson leptoproduction is calculated within the nonrelativistic
QCD framework for the first time. It is found that the colour-singlet channel,
although suppressed by a factor of $\alpha_s$ relative to the colour-octet
ones, provides the most important contribution for almost all the experimental
conditions, which disagrees with some of the expectations before computation.
We present the differential cross sections with respect to $p_t^2$,
$p_t^{\star2}$, $Q^2$, $W$, and $z$, for both HERA and EIC experimental
conditions as a reference for future studies. The scale dependence and
long-distance-matrix-element dependence are also investigated in this paper.
