Abstract: An electrostatic spray painting apparatus includes an electrically-insulated intermediate reservoir for storing therein conductive paint to which a high voltage is directly applied. In addition, the intermediate reservoir includes a cylinder, a piston reciprocatively and slidably disposed within the cylinder, and a fluid-flow straightening member protrudently formed in a part of a cylinder chamber used to be charged with the paint. The cylinder chamber is defined by the cylinder and the piston. An injection hole is defined near an outer peripheral edge of a cylinder wall so as to be connected to a paint and cleaning fluid feed source. A discharge hole is centrally defined in the cylinder wall so as to be connected to a spray gun, the discharge hole being used to discharge the paint and the cleaning liquid.