PURPOSE: To rise the roll temperature, improve the bonding properties of resin with the rolls and release the resin from the rolls by forming two or more heat transfer medium flow paths of different structure concentrically in the longtudinal direction of rolls in the circumferential direction of rolls, flowing heat transfer mediums of different temperature into respective heat transfer medium paths and controlling the temperature of rolls.

CONSTITUTION: Molten resin extruded by an extruder 1 is formed into a sheet by means of a die 2. A first pressure roll 3 is connected with a heating and cooling device 6, and a second pressure roll 4 is connected with heating and cooling devices 7 and 8, while a third pressure roll 5 is connected with heating and cooling devices 9 and 10 respectively, and temperature-adjusted heat transfer medium is circulated in respective pressure rolls and heating and cooling devices to control the temperature of pressure rolls. A second heat transfer flow path 26 is formed in the circumferential direction close to the surface of the second pressure roll 4 on the outside of first heat transfer medium flow path 20 formed cylindrically in said second pressure roll 4, and communicated with a second heat transfer medium flow path 24 formed on an end small diameter section 15 along the longitudinal direction through a communicating path 25 in the vertical direction.