A multi-stage, multi-aperture electrostatic accelerator for hydrogen negative ions has being developed to demonstrate 1 MeV, ampere-class H- beam acceleration. The accelerator consists of an extractor and a five stage accelerator supported and insulated by fiber reinforced plastic (FRP) cylinders. Forty nine apertures were drilled on each electrode. Diameter of the aperture is 14 mm in the extractor and 16 mm in the accelerator. Whole dimensions of the accelerator are 2 m in diameter and 2.5 m in height. The accelerator was conditioned up to a voltage of 920 kV without beam. A highest beam energy of 868 keV with an acceleration current of 19 mA for a duration of 1 s was obtained from nine apertures. An optimum beam perveance agreed well to the beam trajectory simulation. ©1998 American Institute of Physics.