  We report a discovery of diffuse X-ray emission around the supernova remnant
(SNR) G106.3+2.7, which is associated with VER J2227+608 and HAWC J2227+610 and
is known as a candidate for a PeV cosmic ray accelerator (PeVatron). We analyze
observational data of Suzaku around the SNR and the adjacent pulsar PSR
J2229+6114. We find diffuse X-ray emission that is represented by either
thermal or non-thermal one. However, the metal abundance for the thermal
emission is <0.13 Z_sun, which may be too small in the Milky Way and suggests
that the emission is non-thermal. The intensity of the diffuse emission
increases toward PSR J2229+6114 in the same way as radio emission, and it is in
contrast with gamma-ray emission concentrated on a molecular cloud. The X-ray
photon index does not change with the distance from the pulsar and it indicates
that radiative cooling is ineffective and particle diffusion is not extremely
slow. The X-ray and radio emissions seem to be of leptonic origin and the
parent electrons may originate from the pulsar or its wind nebula. The
gamma-ray emission appears to be of hadronic origin because of its spacial
distribution. The parent protons may be tightly confined in the cloud
separately from the diffusing electrons.
