Neutrino oscillation is a probe for new physics not included in the Standard Model. We search for muon neutrino disappearance at \Delta m^2 ~ 1 eV^2 using the Fermilab Booster Neutrino beamline and two experiments, SciBooNE and MiniBooNE. The neutrino fluxes are measured at SciBooNE and MiniBooNE detectors, located at 100 m and 540 m downstream from the neutrino production target, respectively. We took beam data from June 2007 through August 2008 at SciBooNE and MiniBooNE. A preliminary result of the flux measurement at SciBooNE and SciBooNE-MiniBooNE joint oscillation analysis will be presented.