We propose a self-consistent mechanism to estimate the size of the acceleration region in the outer magnetosphere of pulsars (outer gap) and calculate the high-energy radiation produced by the synchrocurvature mechanism from the outer gap. We Dnd that a power-law energy distribution of the accelerated particles can be obtained if the outer gap is thick enough that E•B inside the gap can be approximately proportional to (Ωr/c)1/2B(r). We apply our model to explain X-rays and γ-rays from Geminga and PSR B1055-52, whose outer gaps may occupy～70% of the outer magnetosphere region. If the radius of curvature near the light cylinder of the medium outer gap is larger than the dipolar structure, then perhaps this model may also apply to PSR B1951+32, PSR B1706-44, and others.