A fixing device which may include a flexible cylindrical member which has an inner peripheral surface and is configured to rotate about an axis, a heater arranged inside the cylindrical member and extends in an axial direction of the cylindrical member, and a nip member. The nip member may include a contact surface configured to contact the cylindrical member, and has a predetermined length in a sheet conveying direction. Further, the nip member may have an axial length which includes a predetermined range, wherein the predetermined range along the axial length represents a maximum width of a recording sheet upon which a developer image is fixed. The fixing device may also include a guide member. The guide member and the nip member may be at least partially separated along the predetermined range of the nip member within the predetermined length of the contact surface in the sheet conveying direction.