A method for producing contents filled in a container comprising steps of introducing a polyester container with a non-crystallized neck portion into a sterilized closed space having sterility and closed state on a commercial basis and comprising at least space in which a bottle sterilizing process is performed, space in which a filling process is performed and space in which a sealing process is performed, entire inner surface of said sterilized closed space and surface of an apparatus disposed in said sterilized closed space being sterilized by wet heating of the space using heated water and/or steam, at least the space in which the filling process is performed and the space in which the sealing process is performed being kept under a positive pressure by sterilized air; heating and sterilizing the container at least in its inner surface by wet heating using hot water and/or steam; and filling the contents in the sterilized container at a filling temperature within a temperature range from 40°C to a temperature less than glass transition temperature which is determined by moisture content of the container and then sealing the container.