A fixing device of the present invention includes a holding frame placed along a fixed pressing member. The holding frame includes a groove section having a recessed cross section and extending along the width direction of a sheet. The fixed pressing member is housed in the groove section. The fixed pressing member is pressed toward the rotor so that the rotor and the fixed pressing member are put in pressure contact with each other. A first engaging element is provided in a predetermined position on the bottom face of the groove section of the holding frame. A second engaging element which engages with the first engaging element is provided in a position on the fixed pressing member which corresponds to the positions of the first engaging element on the holding frame.