  We review recent studies on exotic states at the Belle experiment. The
results include: (1) The measurement of the cross sections of $\gamma \gamma
\to \omega \phi$, $\phi\phi$, and $\omega \omega$ for masses that range from
threshold to 4.0 GeV. In addition to signals from well established spin-zero
and spin-two charmonium states, there are clear resonant structures below
charmonium threshold, which have not been previously observed. We report a
spin-parity analysis for the new structures; (2) No X(3872) signal is observed
in $\eta J/\psi$ or $\gamma \chi_{c1}$ mode in B decays. A narrow peak at
3823.5 MeV/$c^2$ (named as $\psi_2$) to $\gamma \chi_{c1}$ with a significance
of 4.2 standard deviations including systematic uncertainty is observed in
$B^{\pm} \to K^{\pm} \gamma \chi_{c1}$; (3) The bottomonium states $h_b(1P)$,
$h_b(2P)$ and $\Upsilon(1D)$ are observed in the reaction $e^+e^- \to \pi^+
\pi^- + X$; (4) The observation of two narrow charged structures (named as
$Z_b(10610)$ and $Z_b(10650)$) in the mass spectra of the
$\pi^{\pm}\Upsilon(nS) (n=1,2,3)$ and $\pi^{\pm} h_b(mP)$ $(m=1,2)$ pairs that
are produced in association with a single charged pion in Y(5S) decays.
