  We report on results of imaging and spectral studies of X-ray emission from
Jupiter observed by Suzaku. In 2006 Suzaku had found diffuse X-ray emission in
$1\unicode{x2013}5$ keV associated with Jovian inner radiation belts. It has
been suggested that the emission is caused by the inverse-Compton scattering by
ultra-relativistic electrons ($ \sim 50 $ MeV) in Jupiter's magnetosphere. To
confirm the existence of this emission and to understand its relation to the
solar activity, we conducted an additional Suzaku observation in 2014 around
the maximum of the 24th solar cycle. As a result, we successfully found again
the diffuse emission around Jupiter in $1\unicode{x2013}5$ keV and also
point-like emission in $0.4\unicode{x2013}1$ keV. The luminosity of the
point-like emission which was probably composed of solar X-ray scattering,
charge exchange, or auroral bremsstrahlung emission increased by a factor of $
\sim 5$ with respect to 2006, most likely due to an increase of the solar
activity. The diffuse emission spectrum in the $1\unicode{x2013}5$ keV band was
well-fitted with a flat power-law function ($ \Gamma = 1.4 \pm 0.1 $) as in the
past observation, which supported the inverse-Compton scattering hypothesis.
However, its spatial distribution changed from $ \sim 12 \times 4 $ Jovian
radius (Rj) to $ \sim 20 \times 7 $ Rj. The luminosity of the diffuse emission
increased by a smaller factor of $ \sim 3 $. This indicates that the diffuse
emission is not simply responding to the solar activity, which is also known to
cause little effect on the distribution of high-energy electrons around
Jupiter. Further sensitive study of the spatial and spectral distributions of
the diffuse hard X-ray emission is important to understand how high-energy
particles are accelerated in Jupiter's magnetosphere.
