  Discovery of coherent pulsations from several ultraluminous X-ray pulsars
(ULXPs) has provided direct evidence of super-critical accretion flow. However,
geometrical structure of such accretion flow onto the central neutron star
remains poorly understood. NGC 5907 ULX1 is one of the most luminous ULXPs with
the luminosity exceeding $10^{41}~{\rm erg~s^{-1}}$. Here we present a
broadband X-ray study of this ULXP using the data from simultaneous
observations with XMM-Newton and NuSTAR conducted in July 2014. The
phase-resolved spectra are well reproduced by a model consisting of a
multicolor disk blackbody emission with a temperature gradient of $p = 0.5~(T
\propto r^{-p})$ and a power law with an exponential cutoff. The disk component
is phase-invariant, and has an innermost temperature of $\sim 0.3~{\rm keV}$.
Its normalization suggests a relatively low inclination angle of the disk, in
contrast to the previous claim in other literature. The power law component,
attributed to the emission from the accretion flow inside the magnetosphere of
the neutron star, indicates phase-dependent spectral shape changes; the
spectrum is slightly harder in the pre-peak phase than in the post-peak phase.
This implies that the magnetosphere has an asymmetric geometry around the
magnetic axis, and that hotter regions close to the magnetic pole become
visible before the pulse peak.
