The self-closing and opening device (1) particularly of a movable furniture part (103) comprises a fixed guide (8) having a supporting body (2) in which a first slider (3) can slide reversibly along a sliding axis (100) in opposition to and through the action of first elastic means (5), the first slider (3) being engageable with first driving means (106) present on a driving element (6) which slides reversibly in the direction of the sliding axis (100), the supporting body (2) comprising first movement means (4) for movement of the first slider (3) suitable to engage with guide means (12, 13) of the first slider (3), so as to release it from the driving means (106), also provided with a mechanical or elastically yielding stop (9, 120) against which the first slider (3) rests directly or indirectly before it engages with the guide means (12,13) in the first movement means (4) the driving element (6) being then pushed by an ejector (20) generating an initial opening movement of said movable furniture part (103).