  We present an investigation of the supernova remnant (SNR) G306.3$-$0.9 using
archival multi-wavelength data. The Suzaku spectra are well described by
two-component thermal plasma models: The soft component is in ionization
equilibrium and has a temperature $\sim$0.59 keV, while the hard component has
temperature $\sim$3.2 keV and ionization time-scale $\sim$$2.6\times10^{10}$
cm$^{-3}$ s. We clearly detected Fe K-shell line at energy of $\sim$6.5 keV
from this remnant. The overabundances of Si, S, Ar, Ca, and Fe confirm that the
X-ray emission has an ejecta origin. The centroid energy of the Fe-K line
supports that G306.3$-$0.9 is a remnant of a Type Ia supernova (SN) rather than
a core-collapse SN. The GeV gamma-ray emission from G306.3$-$0.9 and its
surrounding were analyzed using about 6 years of Fermi data. We report about
the non-detection of G306.3$-$0.9 and the detection of a new extended gamma-ray
source in the south-west of G306.3$-$0.9 with a significance of
$\sim$13$\sigma$. We discuss several scenarios for these results with the help
of data from other wavebands to understand the SNR and its neighborhood.
