Adjustable closing device (10; 110) suitable to be applied to a first flap (A; C) and to a second flap (B; D) of a shoe or article of clothing, so as to keep the first flap (A; C) and the second flap (B; D) at a certain distance or to free them from each other, said adjustable closing device (10; 110) comprising a first connection element (12; 112) and a second connection element (14; 114), the first connection element (12; 112) including: - a first fixing portion (16; 116) suitable for the connection of the first connection element (12; 112) with the first flap (A; C); - a tongue (20; 120) fixed to the first fixing portion (16; 116); the second connection element (14; 114) including: - a second fixing portion (30; 124) suitable for the connection of the second connection element (14; 114) with the second flap (B; D); - a grasping device (34; 126) fixed to the second fixing portion (30; 124) and adapted to grasp the tongue (20; 120) and keep it fixed in a given position or release the tongue (20; 120) so as to free the first flap (A; C) from the second flap (B; D); in which the grasping device (34; 126) includes: - a box-shaped body (42; 128) which has a seat (44; 138) and in which a first slot (46; 137) and a second slot (48; 139) are formed through which the tongue (20; 120) can pass; - locking means (45, 52, 62; 142, 144) suitable to be received in the seat (44; 138) so as to lock or release the tongue (20; 120); wherein the first slot (46; 137) and the second slot (48; 139) are formed in the box-shaped body (42; 128) in a lower position than the second fixing portion (30; 124), so that the tongue (20; 120), once crossed the first slot (46; 137) and the second slot (48; 139), is arranged below the second flap (B; D); wherein the first connection element (12; 112) includes a first gripping portion (18; 118) and the second connection element (14; 114) includes a second gripping portion (32; 133), the first gripping portion (18; 118) and the second gripping portion (32; 133) being adapted to facilitate gripping by the user of the adjustable closing device (10; 110); wherein the first gripping portion includes a first wall (26; 118) and the second gripping portion includes a second wall (40; 133); characterized by the fact that a cavity with seizing means is formed in the first gripping portion and a cavity with seizing means is formed in the second gripping portion. the first connection element (12; 112) including: - a first fixing portion (16; 116) suitable for the connection of the first connection element (12; 112) with the first flap (A; C); - a tongue (20; 120) fixed to the first fixing portion (16; 116); - a first fixing portion (16; 116) suitable for the connection of the first connection element (12; 112) with the first flap (A; C); - a tongue (20; 120) fixed to the first fixing portion (16; 116); the second connection element (14; 114) including: - a second fixing portion (30; 124) suitable for the connection of the second connection element (14; 114) with the second flap (B; D); - a grasping device (34; 126) fixed to the second fixing portion (30; 124) and adapted to grasp the tongue (20; 120) and keep it fixed in a given position or release the tongue (20; 120) so as to free the first flap (A; C) from the second flap (B; D); - a second fixing portion (30; 124) suitable for the connection of the second connection element (14; 114) with the second flap (B; D); - a grasping device (34; 126) fixed to the second fixing portion (30; 124) and adapted to grasp the tongue (20; 120) and keep it fixed in a given position or release the tongue (20; 120) so as to free the first flap (A; C) from the second flap (B; D); in which the grasping device (34; 126) includes: - a box-shaped body (42; 128) which has a seat (44; 138) and in which a first slot (46; 137) and a second slot (48; 139) are formed through which the tongue (20; 120) can pass; - locking means (45, 52, 62; 142, 144) suitable to be received in the seat (44; 138) so as to lock or release the tongue (20; 120); - a box-shaped body (42; 128) which has a seat (44; 138) and in which a first slot (46; 137) and a second slot (48; 139) are formed through which the tongue (20; 120) can pass; - locking means (45, 52, 62; 142, 144) suitable to be received in the seat (44; 138) so as to lock or release the tongue (20; 120); wherein the first slot (46; 137) and the second slot (48; 139) are formed in the box-shaped body (42; 128) in a lower position than the second fixing portion (30; 124), so that the tongue (20; 120), once crossed the first slot (46; 137) and the second slot (48; 139), is arranged below the second flap (B; D); wherein the first connection element (12; 112) includes a first gripping portion (18; 118) and the second connection element (14; 114) includes a second gripping portion (32; 133), the first gripping portion (18; 118) and the second gripping portion (32; 133) being adapted to facilitate gripping by the user of the adjustable closing device (10; 110); wherein the first gripping portion includes a first wall (26; 118) and the second gripping portion includes a second wall (40; 133); characterized by the fact that a cavity with seizing means is formed in the first gripping portion and a cavity with seizing means is formed in the second gripping portion.