A device for closing and fastening two sections of flexible band, particularly two end sections (15a, 15b) of flexible belt band, is equipped with fastening elements (1), which include an end keeper (2), intend to be fixed to a first band section (15a), and a lateral keeper (3), intend to come at the second band section (15b) which the second band section intend to come at the two keepers (2, 3) during closing and fastening operations, by being successively introduced, starting from the lateral keeper (3), through the opening (5) of the end keeper (2), the rear opening (9) of the lateral keeper (3) and the front opening (8) of this same lateral keeper (3), so as to be folded into a generally S-shape, with three superimposed portions (15b1, 15b2, and 15b3).