An apparatus adapted for sterilizing a preform comprising: a traveling unit adapted for transferring a preform and a bottle from a suppling stage of the preform to a molding stage of the bottle; a chamber to which exhaust means composed of a filter adapted for filtrating the air inside the chamber and a blower is connected, such that the apparatus is adapted to remove surplus hydrogen peroxide sterilizer gas discharged from a hydrogen peroxide sterilizer gas supplying nozzle by the filter and to discharge the surplus hydrogen peroxide sterilizer gas outside the chamber, wherein the apparatus is adapted such that the supply amount into or exhaust amount from the chamber is adjusted to create a pressure in the chamber lower than atmospheric pressure; the nozzle adapted for supplying a hydrogen peroxide sterilizer gas to the preform in the chamber, an air nozzle that is adapted for activating the hydrogen peroxide sterilizer adhering to the preform and sterilizing the bacteria adhering to the preform and removing the hydrogen peroxide sterilizer adhering to the preform by blasting a hot air to the preform; a heating furnace adapted for heating the preform to a temperature for a blow-molding treatment; and a mold adapted for blow molding the preform into a bottle, wherein the hydrogen peroxide sterilizer gas supplying nozzle, the hot air supplying nozzle, the heating furnace and the mold are arranged in subsequently form an upstream side toward a downstream side of the traveling unit, and wherein the chamber and the heating furnace are located within a clean room to prevent bacteria and fungus from invading into the chamber under negative pressure. a traveling unit adapted for transferring a preform and a bottle from a suppling stage of the preform to a molding stage of the bottle; a chamber to which exhaust means composed of a filter adapted for filtrating the air inside the chamber and a blower is connected, such that the apparatus is adapted to remove surplus hydrogen peroxide sterilizer gas discharged from a hydrogen peroxide sterilizer gas supplying nozzle by the filter and to discharge the surplus hydrogen peroxide sterilizer gas outside the chamber, wherein the apparatus is adapted such that the supply amount into or exhaust amount from the chamber is adjusted to create a pressure in the chamber lower than atmospheric pressure; the nozzle adapted for supplying a hydrogen peroxide sterilizer gas to the preform in the chamber, an air nozzle that is adapted for activating the hydrogen peroxide sterilizer adhering to the preform and sterilizing the bacteria adhering to the preform and removing the hydrogen peroxide sterilizer adhering to the preform by blasting a hot air to the preform; a heating furnace adapted for heating the preform to a temperature for a blow-molding treatment; and a mold adapted for blow molding the preform into a bottle, wherein the hydrogen peroxide sterilizer gas supplying nozzle, the hot air supplying nozzle, the heating furnace and the mold are arranged in subsequently form an upstream side toward a downstream side of the traveling unit, and wherein the chamber and the heating furnace are located within a clean room to prevent bacteria and fungus from invading into the chamber under negative pressure.