The effect of stress ratio (R=σ_min/σ_max) on subsurface fatigue fracture of high-speed tool steel, SKH51, was investigated using smooth specimen subjected to axial reversed loading in air at room temperature. From the experimental results, interior inclusion induced fracture occurred in each stress ratio. The number of cycles to the transition from surface fracture mode to subsurface fracture mode depended on R. A granular-bright-facet (GBF) area formed around the nonmetallic inclusion inside the fish-eye zone on the fracture surface of the specimen in long-life fatigue regime, N_f>106, at R=-1.3, -1 and 0. From the detail observation of GBF area by three-dimensional SEM, the roughness of GBF area depended on the stress intensity factor range, Δk_{inc, s,} at the inclusion of facture origin.