It is aimed to eliminate charges accumulated inside a wall structure of a resin vessel (2), which is sterilized by an electron beam irradiator (16), and an ionizer (134) disposed outside a filler (112) emits to the outer surface of the resin vessel (2) with negative ions having the same polarity as that of charges accumulated in the wall section of the resin vessel (2), while conveying the resin vessel (2) sterilized by the electron beam irradiator (16) to the filler (112), by which liquid fills the resin vessel (2). A filling nozzle (132) is connected to ground, and an ion flowing path is formed through a liquid column (La) filling the interior of the resin vessel (2) from the filling nozzle (132). The ions having the negative charges in a filling liquid (L) flow toward ground side of the ionizer (134), and on the other hand, ions having positive charges are attracted to the inner surface of the resin vessel (2) to thereby neutralize the charges remaining inside the wall structure of the resin vessel (2) with the ions having the positive charges.
