A fixing device for fixing image information on a recording medium passing a nip of the present invention includes a rotatable member for transferring and conveying a non-fixed image, a first heating means for heating an image present on the rotatable member and a rotatable pressing member forming a nip in combination with the rotatable member. A heat pipe extends in parallel to the axis of the rotatable member. A radiating member is positioned at one end of the heat pipe while a heating member is positioned at the other end of the heat pipe.