An underactuated prosthetic hand (1) is provided comprising a base body (2)； a pair of prosthetic fingers (3) comprising a first prosthetic finger (3) and a second prosthetic finger (3)； each finger is hinged to the base body (2)； a first control cable (5a)； an actuator (4) adapted to move the first control cable (5a)； and for each pair of prosthetic fingers (3) a second control cable (5b) having control ends associated with the first prosthetic finger (3) and the second prosthetic finger (3)； and a transmission block (6) adapted to allow the first control cable (5a) to control the second control cable (5b)； said transmission block (6) comprises a guide (61) integral with the base body (2) and defining a sliding axis (61a)； a movable element (62) sliding along the guide (61)； a first pulley (64) for the sliding of the first control cable (5a) hinged to the movable element (62) and a second pulley (65) for the sliding of the second control cable (5b) hinged to the movable element (62) so that the actuator (4), when moving the first cable (5a), determines a translational movement of the movable element (62) causing a displacement of the second control cable (5b) and therefore of the prosthetic fingers (3)； and elastic means (63) adapted to work in opposition to the translational movement of the movable element (62) so that said translational movement of the movable element (62) is performed in opposition to the elastic means (63) allowing them to facilitate the return to the initial position of the movable element (62).La présente invention concerne une prothèse de main sous-actionnée (1) comprenant un corps de base (2)； une paire de doigts prothétiques (3) comprenant un premier doigt prothétique (3) et un second doigt prothétique (3)； chaque doigt est articulé sur le corps de base (2)； un premier câble de commande (5a)； un actionneur (4) conçu pour déplacer le premier câble de commande (5a)； et pour chaque paire de doigts prothétiques (3) un second câble de commande
