A fixing device that is configured to fix an image formed on a recording material to the recording material at a fixing nip portion, the fixing device comprising: a flexible cylindrical rotary member that is configured to rotate while contacting the recording material on which the image has been formed; a roller that forms the fixing nip portion and that is configured to nip and to convey the recording material together with the rotary member; a first movable member (11, 21, 31, 111, 611) that opposes one end surface of the rotary member in a generatrix direction of the rotary member, the first movable member including a first inner-surface opposing portion (11c, 21c, 31c, 111c, 611c) and a first end-surface opposing portion (11a, 21a, 31a, 111a, 611a), the first inner-surface opposing portion opposing an inner surface of the rotary member at one end portion of the rotary member in the generatrix direction, the first end-surface opposing portion opposing the one end surface of the rotary member; and a second movable member (11, 21, 31, 111, 611) that opposes the other end surface of the rotary member in the generatrix direction of the rotary member, the second movable member including a second inner-surface opposing portion (11c, 21c, 31c, 111c, 611c), and a second end-surface opposing portion (11a, 21a, 31a, 111a, 611a), the second inner-surface opposing portion opposing an inner surface of the rotary member at the other end portion of the rotary member in the generatrix direction, the second end-surface opposing portion opposing the other end surface of the rotary member, wherein the first and second movable members are provided movably toward an upstream side (M2, M3, M4) at the fixing nip portion in a recording material conveying direction, wherein the fixing device is configured such that, when the rotary member is laterally shifted in the generatrix direction and pushes the first end-surface opposing portion, the first movable member moves to an upstream side in a recording material conveying direction at the fixing nip portion by a force for pushing the first end-surface opposing portion by the rotary member, and the first inner-surface opposing portion pushes the inner surface of one end of the rotary member in the generatrix direction to the upstream side in the recording material conveying direction, and when the rotary member is laterally shifted in the generatrix direction and pushes the second end-surface opposing portion, the second movable member moves to the upstream side in the recording material conveying direction at the fixing nip portion by a force for pushing the second end-surface opposing portion by the rotary member, and the second inner-surface opposing portion pushes the inner surface of the other end of the rotary member in the generatrix direction to the upstream side in the recording material conveying direction. a flexible cylindrical rotary member that is configured to rotate while contacting the recording material on which the image has been formed; a roller that forms the fixing nip portion and that is configured to nip and to convey the recording material together with the rotary member; a first movable member (11, 21, 31, 111, 611) that opposes one end surface of the rotary member in a generatrix direction of the rotary member, the first movable member including a first inner-surface opposing portion (11c, 21c, 31c, 111c, 611c) and a first end-surface opposing portion (11a, 21a, 31a, 111a, 611a), the first inner-surface opposing portion opposing an inner surface of the rotary member at one end portion of the rotary member in the generatrix direction, the first end-surface opposing portion opposing the one end surface of the rotary member; and a second movable member (11, 21, 31, 111, 611) that opposes the other end surface of the rotary member in the generatrix direction of the rotary member, the second movable member including a second inner-surface opposing portion (11c, 21c, 31c, 111c, 611c), and a second end-surface opposing portion (11a, 21a, 31a, 111a, 611a), the second inner-surface opposing portion opposing an inner surface of the rotary member at the other end portion of the rotary member in the generatrix direction, the second end-surface opposing portion opposing the other end surface of the rotary member, wherein the first and second movable members are provided movably toward an upstream side (M2, M3, M4) at the fixing nip portion in a recording material conveying direction, wherein the fixing device is configured such that, when the rotary member is laterally shifted in the generatrix direction and pushes the first end-surface opposing portion, the first movable member moves to an upstream side in a recording material conveying direction at the fixing nip portion by a force for pushing the first end-surface opposing portion by the rotary member, and the first inner-surface opposing portion pushes the inner surface of one end of the rotary member in the generatrix direction to the upstream side in the recording material conveying direction, and when the rotary member is laterally shifted in the generatrix direction and pushes the second end-surface opposing portion, the second movable member moves to the upstream side in the recording material conveying direction at the fixing nip portion by a force for pushing the second end-surface opposing portion by the rotary member, and the second inner-surface opposing portion pushes the inner surface of the other end of the rotary member in the generatrix direction to the upstream side in the recording material conveying direction.