Abstract: An attachment device for adjustably mounting the neck to the body of a stringed musical instrument, for example a banjo, has a pair of plates for attachment respectively to the neck and body of the banjo. A pivot point locates one plate with respect to the other, and a pair of adjustment screws interconnect the plates, cooperatively controlling the angle at which the neck extends away from the body. Elongated holes in one of the adapter plates receive the adjustment screws, permitting the neck to be rotated with respect to the body, about the longitudinal axis of the neck. The device may include a brace bar extending across the body of the instrument to hold a tailpiece. A setscrew opposes tension in the adjustment screws to hold the plates in desired relative positions.