The invention relates to a surgical instrument (100; 200) comprising: an elongated arm (111; 207) according to a longitudinal axis and having a distal end (105; 204) mounted with a pivot joint on the elongated arm according to an axis substantially orthogonal to the longitudinal axis; a drive shaft (103; 3), substantially coaxial with the elongated arm, comprising means forming a universal joint (104; 206) facing the pivot joint; and, distal tool (9) securely fastened on the drive shaft and rotatively mounted on and in the extension of the distal end of the elongated arm, such that the distal tool has two rotational degrees of freedom, distinct and independent of each other, one being around an axis substantially perpendicular to the longitudinal axis of the elongated arm and the other being around an axis substantially collinear to an own axis of the distal tool, characterized in that the means forming a universal joint comprise a flexible drive sleeve (104; 206).