A hand rehabilitation device comprising a thumb rehabilitation assembly (20) and a thumb fixing mechanism (40) coupled thereto for the anthropometric positioning of a thumb of a user. The thumb fixing mechanism (40) comprises: a fixing/releasing mechanism (10, 110) comprising an elongated member (1, 1) a first part (2) comprising a through hole for sliding said part (2) along said elongated member (1, 1) a joint (8) comprising two parallel hollow canals (3A, 4A, 6A 3B, 4B, 6B) that go through the joint (8) from a first side to a second side thereof, opposite to the first side, said joint (8) comprising a through hole (3C, 4C, 6C) configured to mount the joint (8) concentrically along said elongated member (1, 1) until the joint (8) is supported on said first part (2) guiding means (5) comprising two sections (5A, 5B) inserted along respective said two parallel hollow canals (3A, 4A, 6A 3B, 4B, 6B), said two sections (5A, 5B) being capable of sliding along said canals (3A, 4A, 6A 3B, 4B, 6B), wherein one end (5x, 5y) of each of said two sections (5A, 5B) are connected to said thumb rehabilitation assembly (20) a nut (7) configured to be concentrically mounted on said joint (8) along said elongated member (1, 1). The fixing/releasing mechanism (10, 110) is configured to manually switch from a first position to a second position and vice versa: a first unlocked position in which the joint (8) and the guiding means (5) are free to perform a plurality of independent movements in different directions for adjusting said thumb rehabilitation assembly (20) and a second locked position in which the movement of said joint (8) and guiding means (5) is blocked, thus fixing the thumb rehabilitation assembly (20) in the position selected after performing said plurality of independent movements.
