A peg mechanism and peg for stringed instruments is provided. It requires no skilled techniques and dedicated tools for manufacturing and maintaining instruments easily. It is applicable to the existing instruments, easy to perform tuning and fine-tuning, and usable for a long time period in stable A certain number of cylindrical throughholes, each having an inner surface with an axially uniform diameter, are provided along the extending direction of strings and sequentially on a support wall formed in a head stock of a stringed instrument. A bushing composed of a abrasion quality material is sandwiched between a string post for winding a string and a knob for rotating the string post, and secured in the throughhole. An adjusting means is provided between the string post and the knob for relatively displacing the string post close to and apart from the knob by external operations.