A truss rod adjustment device includes a truss rod gear assembly, an adjustment gear assembly and a base. The truss rod gear assembly includes an end shaped to fit in and engage a truss rod wrench socket attached to a neck of a guitar. The adjustment gear assembly includes an adjustment socket shaped to receive and engage a wrench. The base attaches to the neck of the guitar and holds the truss rod gear assembly in position to engage the truss rod wrench socket. The base also holds the adjustment gear assembly in position both to engage the truss rod assembly gear assembly and to position the adjustment socket to be accessible through a hole in a back of the guitar.