The invention relates to an instrument (12) which comprises: a tool (24) a tool-holder (26) complementary means (30) for vibrational coupling of the tool (24) to the tool-holder (26) which can be activated by relative movement of the tool (24) and the tool-holder (26) along a vibrational coupling/uncoupling stroke and complementary releasable means (28) for attaching the tool (24) to the tool-holder (26) allowing, when the tool (24) is attached to the tool-holder (26), the vibrational coupling/uncoupling stroke. The attachment means (28) include two attachment members, male (36) and female (38), which can be attached together by relative movement along an attachment/detachment stroke. Said attachment members (36, 38) cannot be deformed during the attachment/detachment stroke. Said stroke includes an axial component and a component in a plane substantially transverse to the axial component, referred to as the transverse component. The axial and transverse components of the attachment/detachment stroke are defined by complementary interlocking shapes (36F, 38F) provided on the two connection members (36, 38).Cet instrument (12) comprend : - un outil (24), - un porte-outil (26), - des moyens complémentaires (30) de couplage vibratoire de loutil (24) au porte-outil (26) activables par déplacement relatif de loutil (24) et du porte- outil (26) suivant une course de couplage-découplage vibratoire, et - des moyens complémentaires libérables (28) dattelage de loutil (24) au porte-outil (26) autorisant, lorsque que loutil (24) est attelé au porte-outil (26), la course de couplage-découplage vibratoire. Les moyens dattelage (28) comportent deux organes dattelage, mâle (36) et femelle (38), attelables entre eux par déplacement relatif suivant une course dattelage- dételage. Ces organes dattelage (36, 38) sont indéformables lors de la course dattelage-dételage. Cette course comporte une composante axiale et une composante dans un plan sensiblement transversal à la composante ax
