PURPOSE: To make a response speed fast against the temperature variation of a resin, by controlling a heating medium circulated in a screw inside according to a deviation value calculated by comparing the detected value of a resin temperature in the vicinity of the delivery port of an extruder with a set value.

CONSTITUTION: A resin material supplied to the hopper 12 of an extruder 11 is heat melted by a heater 13 and a screw 14 where a heating medium is circulated inside and it is delivered from a die 15 via a measuring block 16. A value detected by the block 16 is inputted to the comparing part 19 of a resin temperature detecting apparatus 17 and is compared with the predetermined temperature of a setting instrument 18, and the signal of a deviation is outputted via an amplifier 20. Meanwhile the temperature 23 of the heating medium detected by a control device 21 of the temperature in the screw is inputted to a comparing part 26 in a temperature adjuster 24 and the value of a deviation is determined by comparing it with the predetermined temperature of a setting instrument 25. Then, an addition is made when an output signal from a device 17 is plus and a subtraction is made when is minus, a deviation signal is outputted from the confronting part 26 and is outputted to a relay 29 via the amplifiers 27, 28, thus the temperature control of the heating medium is performed.