A fixing device includes a first rotatable member with a heater, a second rotatable member contacting the first rotatable member and forming a fixing nip, a pressing unit pressing the first rotatable member to the second rotatable member in a pressing direction, a pair of side boards disposed with a space in the widthwise direction, and first, second and third stays supporting the pair of side boards. The first stay is provided upstream of a center of the fixing nip in the pressing direction and upstream of the center in a feeding direction of a recording material. The second stay is provided upstream of the center in the pressing direction and downstream of the center in the feeding direction. The third stay is provided downstream of the center in the pressing direction and at least one of upstream and downstream of the center in the feeding direction.