Strap wrench for driving an object having a generally cylindrical shape, of the type comprising: - a part forming a handle which extends according to a longitudinal axis (X-X); - a strap, in particular a metal strap, in loop form, the two opposing strands (16, 17) of which cooperate with two zones rigidly connected to the handle when the strap tightly surrounds said object; - a connecting member which is movable relative to the part forming a handle according to the longitudinal axis thereof, the two opposing strands of the strap having respective ends that are rigidly connected to said member; - means (30, 40, 46, 88, 130, 132) for moving said connecting member, allowing the size of the loop of the strap to be adjusted and the strap to be tensioned when it tightly surrounds said object; - the part forming a handle being equipped, between said two zones, with a pad for bearing on said object, the bearing pad not being connected to the strap and having a bearing face of generally cylindrical shape having generatrices that are perpendicular to the general plane of the strap, characterised in that said connecting member is movable between at least one first position corresponding to the position of the strap, in the loose state, surrounding said object with clearance, and a second position corresponding to the position of the strap, in the tensioned state, tightly and firmly surrounding said object and bearing on the bearing face of the pad, and in that the movement means comprise: - elements for locking said connecting member, said locking elements being suitable, in the active position, for keeping said member fixed relative to the part forming a handle when said member is in the first position; - a resilient biasing element, in particular a compression or draw spring, which urges said member towards said second position; and - a control member (30, 40, 56) suitable for deactivating said locking elements. - a part forming a handle which extends according to a longitudinal axis (X-X); - a strap, in particular a metal strap, in loop form, the two opposing strands (16, 17) of which cooperate with two zones rigidly connected to the handle when the strap tightly surrounds said object; - a connecting member which is movable relative to the part forming a handle according to the longitudinal axis thereof, the two opposing strands of the strap having respective ends that are rigidly connected to said member; - means (30, 40, 46, 88, 130, 132) for moving said connecting member, allowing the size of the loop of the strap to be adjusted and the strap to be tensioned when it tightly surrounds said object; - the part forming a handle being equipped, between said two zones, with a pad for bearing on said object, the bearing pad not being connected to the strap and having a bearing face of generally cylindrical shape having generatrices that are perpendicular to the general plane of the strap, characterised in that said connecting member is movable between at least one first position corresponding to the position of the strap, in the loose state, surrounding said object with clearance, and a second position corresponding to the position of the strap, in the tensioned state, tightly and firmly surrounding said object and bearing on the bearing face of the pad, and in that the movement means comprise: - elements for locking said connecting member, said locking elements being suitable, in the active position, for keeping said member fixed relative to the part forming a handle when said member is in the first position; - a resilient biasing element, in particular a compression or draw spring, which urges said member towards said second position; and - a control member (30, 40, 56) suitable for deactivating said locking elements.