  We have analyzed 121.4 fb$^{-1}$ of data collected at the $\Upsilon(5S)$
resonance by the Belle experiment using the KEKB asymmetric-energy $e^+e^-$
collider to search for the decay $B_s^0\to J/\psi\pi^0$. We observe no signal
and report an upper limit on the branching fraction $\mathcal{B}(B_s^0\to
J/\psi\pi^0)$ of $1.21\times 10^{-5}$ at 90\% confidence level. This result is
the most stringent, improving the previous bound by two orders of magnitude.
