We report the detection of a time variable O \emissiontype VII line emission in a deep 100 ks Suzaku X-ray Imaging Spectrometer spectrum of the Galactic Ridge X-ray emission .
The observed line intensity is too strong ( 11 \pm 2 line unit or photon cm ^ { -2 } s ^ { -1 } str ^ { -1 } ) to be emitted inside the heavily obscured Galactic disk .
It showed a factor of two time variation which shows a significant ( \sim 4 \sigma ) correlation with the solar wind O ^ { 7 + } ion flux .
The high line intensity and the good time correlation with the solar wind strongly suggests that it originated from geocoronal solar wind charge exchange emission .
We discuss the X-ray line intensity considering a line of sight direction and also theoretical distribution models of the neutral hydrogen and solar wind around the Earth .
Our results indicate that X-ray observations of geocoronal solar wind charge exchange emission can be used to constrain these models .