An exoskeleton device (100) for assisting the movement of a metacarpal-phalangeal joint (50) of a hand in a flexion/extension plane Γ of the joint, comprising a metacarpal support (150) arranged to be kept integral to a metacarpal portion of the hand, a phalangeal support (105) having means for fastening to a proximal phalanx, a kinematical chain between the metacarpal support (150) and the phalangeal support (105) arranged to provide and carry out a rotation of the phalangeal support (105) with respect to the metacarpal support (150). Such kinematical chain comprising in turn a metacarpal slide (101) arranged to slide with respect to the metacarpal support (150) along a predetermined line γ arranged in the plane Γ, a stiff link (103) pivotally connected to the metacarpal slide (101) by a first pivotal constraint (102), a second pivotal constraint (104) arranged to connect pivotally the stiff link and the phalangeal support (105), and an actuating means for causing a first rotation to the stiff link (103) at the first pivotal constraint (102) and a second rotation to the phalangeal support (105) at the second pivotal constraint (104), said actuating means configured for zeroing the constraint forces of the exoskeleton device on the metacarpal-phalangeal joint versus the rotation Θ, for any position of the metacarpal- phalangeal joint (50) with respect to the exoskeleton device, within a predetermined range.Exosquelette (100) destiné à aider le mouvement d'une articulation métacarpo-phalangienne (50) d'une main dans un plan de flexion/extension Γ de l'articulation, qui comprend un support métacarpien (150) conçu pour être maintenu solidaire d'une partie métacarpienne de la main, un support phalangien (105) pourvu de moyens permettant de fixer ledit support à une phalange proximale, une chaîne cinématique entre le support métacarpien (150) et le support phalangien (105) conçue pour provoquer et effectuer une rotation du support phalangien (105) par rapport au support
