Disclosed herein is a method and means for replacing upper and lower corrugated rolls in a single facer having a cassette frame for rotatably supporting the upper and lower rolls and a main frame to which the cassette frame is detachably connected. The method comprises the steps of suspending and moving away the cassette frame apart from a predetermined mounting position in the single facer, keeping a spare cassette rotatably supporting other upper and lower rolls waiting in a suspended condition and fixing the spare cassette frame to the predetermined mounting position in the single facer in place of the cassette frame removed. Means for performing the method is disclosed which comprises a cassette frame rotatably supporting the upper and lower rolls; and a main frame carrying a pressure roll and a gluing unit. The cassette frame is detachably connected to the main frame.