A drying roller includes: a cylindrical member for drying a separator original sheet, with hot water which is supplied into the cylindrical member and ejected from inside the cylindrical member, the separator original sheet being wrapped on an outer peripheral surface of the cylindrical member; and a discharge pipe for discharging the hot water toward one inner end surface of the cylindrical member, the heating medium being discharged at a position where a distance to the one end surface of the cylindrical member is longer than a distance to the other inner end surface of the cylindrical member.