A roping harness comprising thigh loops and a belt provided with a device for adjusting the circumference of the belt, the device for adjusting the circumference of the belt comprising: - a wire element having a first end attached to a first end of the belt, - an apertured part movably mounted on the wire element, the apertured part defining a through hole through which the wire element passes, the through hole opening onto two opposite side walls of the apertured part, roping harness characterized in that: - the wire element is an elastic wire element forming a plurality of undulations at rest, the plurality of undulations having a first amplitude along a first direction, the first amplitude being greater than a lateral dimension of the through hole measured along the first direction, one undulation coming into contact with one of the side walls of the apertured part to block the apertured part along the elastic wire element and wherein the amplitude of the plurality of undulations is reduced or the plurality of undulations disappear when the wire member is under tension along its longitudinal axis, the thickness of the wire member under tension being less than or equal to the lateral dimension of the through hole so as to allow the apertured part to slide along the elastic wire member, the thickness of the elastic wire member under tension being measured along the first direction, and in that - a buckle is attached to the second end of the belt, the buckle abutting the aperture part to close the belt, the buckle defining a passageway having a first cross-section and the aperture part having a shape able to pass through the passageway in a first orientation and to prevent passing through the passageway in a second orientation. - a wire element having a first end attached to a first end of the belt, - an apertured part movably mounted on the wire element, the apertured part defining a through hole through which the wire element passes, the through hole opening onto two opposite side walls of the apertured part, - the wire element is an elastic wire element forming a plurality of undulations at rest, the plurality of undulations having a first amplitude along a first direction, the first amplitude being greater than a lateral dimension of the through hole measured along the first direction, one undulation coming into contact with one of the side walls of the apertured part to block the apertured part along the elastic wire element and wherein the amplitude of the plurality of undulations is reduced or the plurality of undulations disappear when the wire member is under tension along its longitudinal axis, the thickness of the wire member under tension being less than or equal to the lateral dimension of the through hole so as to allow the apertured part to slide along the elastic wire member, the thickness of the elastic wire member under tension being measured along the first direction, and in that - a buckle is attached to the second end of the belt, the buckle abutting the aperture part to close the belt, the buckle defining a passageway having a first cross-section and the aperture part having a shape able to pass through the passageway in a first orientation and to prevent passing through the passageway in a second orientation.