  We report properties of the intracluster medium (ICM) in Abell~1246 to the
virial radius ($r_{200}$) and further outside as observed with Suzaku. The ICM
emission is clearly detected to $r_{200}$, and we derive profiles of electron
temperature, density, entropy, and cluster mass based on the spectral analysis.
The temperature shows variation from $\sim 7$ keV at the central region to
$\sim 2.5$ keV around $r_{200}$. The total mass in $r_{500}$ is $(4.3 \pm 0.4)
\times 10^{14}~M_{\odot}$, assuming hydrostatic equilibrium. At $r>r_{500}$,
the hydrostatic mass starts to decline and we, therefore, employ the total mass
within $r_{200}$ based on weak-lens mass profile obtained from a sample of
lower mass clusters. This yields the gas mass fraction at $r_{200}$ consistent
with the cosmic baryon fraction, i.e. $\sim 17$%. The entropy profile indicates
a flatter slope than that of the numerical simulation, particularly in
$r>r_{500}$. These tendencies are similar to those of other clusters observed
with Suzaku. We detect no significant ICM emission outside of $r_{200}$, and
$2\sigma$ upper limits of redshifted OVII and OVIII line intensities are
constrained to be less than 2.9 and $5.6\times 10^{-7}$ photons cm$^{-2}$
s$^{-1}$ arcmin$^{-2}$, respectively. The OVII line upper limit indicates
$n_{\rm H}< 4.7\times 10^{-5}$ cm$^{-3}$ ($Z/0.2~Z_{\odot}$)$^{-1/2}$
($L/20~{\rm Mpc}$)$^{-1/2}$, which corresponds to an overdensity, $\delta<160$
($Z/0.2~Z_{\odot}$)$^{-1/2}$ ($L/20~{\rm Mpc}$)$^{-1/2}$.
