  We present a search for the charged lepton-flavor-violating decays
$\Upsilon(1S)\rightarrow\ell\ell^\prime$ and radiative charged
lepton-flavour-violating decays $\Upsilon(1S)\rightarrow\gamma\ell\ell^\prime$
[$\ell,\ell^\prime = e, \mu, \tau$] using the 158 million $\Upsilon(2S)$ sample
collected by the Belle detector at the KEKB collider. This search uses
$\Upsilon(1S)$ mesons produced in $\pi^+\pi^-\Upsilon(1S)$ transitions. We do
not find any significant signal, so we provide upper limits on the branching
fractions at the 90% confidence level.
