An image heating apparatus includes a first rotary member, a second rotary member a retaining portion, and a regulating portion. An end portion of the first rotary member abuts against the regulating portion and the regulating portion regulates movement of the first rotary member to the sheet width direction. The regulating portion comprises a curved surface shape having a radius of curvature of 10 mm or greater and 500 mm or smaller and protruding toward the first rotary member. An apex portion of the curved surface shape is, when viewed in the sheet width direction, positioned in an area outside of the retaining portion and on a side of the first rotary member from a tangent of the first rotary member at the nip portion. The apex portion is positioned in an area upstream in the sheet conveyance direction of a straight line that is orthogonal to the tangent.