  The magnetization curve of the two-dimensional spin-1/2 $J_1$-$J_2$
Heisenberg model is investigated by using the Chern-Simons theory under a
uniform mean-field approximation. We find that the magnetization curve is
monotonically increasing for $J_2/J_1 < 0.267949$, where the system under zero
external field is in the antiferromagnetic N\'eel phase. For larger ratios of
$J_2/J_1$, various plateaus will appear in the magnetization curve. In
particular, in the disordered phase, our result supports the existence of the
$M/M_{\rm sat}=1/2$ plateau and predicts a new plateau at $M/M_{\rm sat}=1/3$.
By identifying the onset ratio $J_2/J_1$ for the appearance of the 1/2-plateau
with the boundary between the N\'eel and the spin-disordered phases in zero
field, we can determine this phase boundary accurately by this mean-field
calculation. Verification of these interesting results would indicate a strong
connection between the frustrated antiferromagnetic system and the quantum Hall
system.
