A fixing device according to the present invention includes a fixing belt (21), a cap member (28) attached to an end part (21a) of the fixing belt (21) and an elastic member (29) arranged between the fixing belt (21) and the cap member (28). The cap member (28) includes a main body part (55) covering an outside of the end part (21a) of the fixing belt (21) and a flange part (56) extending from the main body part (55) to an inside and covering an outer diameter side of the end part (21a) of the fixing belt (21). A step (s) is formed in an inner circumference face of the flange part (56). An outer circumference face of the elastic member (29) comes into contact with an inside part from the step (s) in the inner circumference face of the flange part (56).