To suppress the temperature fluctuation of an external rotary body for heating to the minimum without making the device larger and to provide the rotary body or heating efficiency heating a fixing roll from the outside.

The rotary body for heating 2 is provided with a 1st layer forming member 4 having a small thermal expansion coefficient and a 2nd layer forming member 3 arranged on the outside of the member 4 and having the larger thermal expansion coefficient that the member 4; and the members 4 and 3 are deformed in a direction where they are separated due to the difference of the thermal expansion coefficient caused by temperature change.