A holding device to hold a tube or cable in engagement with a bracket is provided with a structure having a seat, which is a through seat along an axis and is defined by a substantially C-shaped edge so as to have a radial opening; the structure further has a slit, which extends along a radial direction up to said seat so as to allow the bracket, in use, to be inserted into the slit and engage the seat; the holding device is further provided with a wing, which is movable between an open position, in which the seat can be accessed through the opening and a closed configuration, in which the opening is closed by the wing.