  The energy spectrum of cosmic-ray antiprotons has been measured by BESS
successively in 1993, 1995, 1997 and 1998. In total, 848 antiprotons were
clearly identified in energy range 0.18 to 4.20 GeV. From these successive
measurements of the antiproton spectrum at various solar activity, we discuss
about the effect of the solar modulation and the origin of cosmic-ray
antiprotons. Measured antiproton ratios were nearly identical during this
period, and were consistent with a prediction taking the charge dependent solar
modulation into account.
